Sunday, 8 November 2026

So You Thought You Knew EVERYTHING About Equilateral Triangles?

  

   



Catching up on some reading lately I came across an interesting book on Academia called Mysteries of the Equilateral Triangle.  The only mystery is why he chose to use that word in the title, but it does include a lot of obscure historical and mathematical tidbits about this basic geometric standard.  I will share a few I like and add a couple of things I've come across in other places to share as well.

The first is in the historical section where he includes an ancient geometric motif from a temple in Chennai, India.  It shows three interlocking triangles, but notice they are interlocked in a Brunnian link, like the famous Borromean Rings.  While the three can not be separated, no two are individually linked.



Along the way he enumerates lots of interesting things about history and property of equilateral triangles that you may well teach, Viviani's theorem, and one of my favorites, Morley's theorem 

Then he mentions two common recreational challenges.  The harder, in my mind, Find the side length and area of the largest square that can be inscribed in an equilateral triangle with unit side lengths. The easier, perhaps, find the side length and area of an the largest equilateral triangle that can be inscribed in a unit square. 

The two are interestingly tied together. 





The Figure above showed up on the wonderful Futility Closet blog a while back. It shows that two simple maximization problems are curiously related.  Problem one, shown in the equilateral triangle at top is the solution to what is the largest square that can be inscribed in an equilateral triangle with unit side lengths. Problem two, shown in the bottom square is the solution to what is the largest equilateral triangle that can be inscribed in a square with unit side lengths.  The coincidence?  The length of the side of the square in the triangle is 2∗3−3 units; and the area of the equilateral triangle in the bottom square, is  2∗3−3 square units. Greg Ross, the mastermind behind the Futility Closet blog credits John Conway with discovering the proof of this relationship.

Digressing a moment from equilateral triangles, another couple of relationships I came across that, somehow, lead me back to the same topic in a roundabout way.

 I'm strolling through my twitter feed, and Colin Beveridge AKA @icecolbeveridge posted one of his always entertaining "Math Ninja" blogs and it was about Ailles Rectangle. He just showed that it was a great memory device to figure out the trigonometric values of 15o and 75o. It is easy to construct and a nice way to verify directly the sum and addition formulas.
 I had seen the Ailles (pronounced like the beverage, by coincidence) rectangle several years before, (it's been around even before I was a teacher, but seems not very well known) and had to do a little research to figure out why Colin's looked different.

I found an article by Jack S. Calcut at Oberlin College. He gave the original Ailles rectangle from the 1971 article, and sure enough it was different. (Chris Maslanka pointed out that the segment in the upper left should be 3−1

Where Colin had a 30-60-90 triangle inscribed in the rectangle, Ailles had used an isosceles right triangle. Both however, contain the three essential triangles necessary to demonstrate, what I believe is it's great power as a classroom demonstration, they contain ALL of the right triangles that exist with rational angles and each side length containing at most one square root.  There is a 30-60-90, a 45-45-90, and a 15-75-90 triangle. That's it, that's all of them, there are no others. And that seems to be impressive as heck to high school students.  "Here they are, memorize this image and you have the whole set!"  And all those Pythagorean triples you know how to create.... None of them have rational angles in degree measure or as multiples of π.

Since the theme of the day is coincidences, I noticed that the diagrams of Ailles contained another somewhat well known historical result.; If you look  remove the 15-75-90  triangle  at the top, you are left with a trapezoid that is used in the proof of the Pythagorean Theorem by President James Garfield of the US . Garfield was a professor of mathematics at Hiram College in Ohio for several years before being elected to the Ohio Senate in 1859. He was in congress, not president,when he did the proof which was published in the New England Journal of Education in 1876.

As I was studying Conway's curiosity,  I realized that there was one more coincidence between the diagram and Ailles rectangle.   Using Colin's illustration, if you reflect the 30-60-90 triangle about its longest leg and extend the other lines it will look like this.  

Constructing the Equilateral Triangle at the bottom side of the figure and we have Conway's figure rotated 180 degrees.  So Garfield's Pythagorean proof, with an additional triangle becomes the Ailles Rectangle showing all the rational right triangles with sides with a single quadratic root; and reflecting part of that gives us the square that demonstrates a curious equality between two classic maximization problems.  I imagine you could assemble the whole thing out of tiles available for the elementary school. 



Another little know truth the book reveals is that if you find the Euler Line in a triangle with a 60 degree angle, the Euler line will cut off an equilateral triangle.


Ok, how about creating a parabolic arc with equilateral triangles?  Simply done by erecting equilateral triangles along a straight line with progressive side lengths of the odd numbers.



Another novelty to let your students discover, take an equilateral triangle and circumscribe it in a rectangle.  (there are several ways to do that, so they should do a couple each.  Now find the area of the three new triangles created inside the rectangle but outside the equilateral triangle.  Make an observation.  One they may pick up after some thought, if we call the three area A, B, and C, then there will always be one that is the sum of the other two.  

Two of my favorite equilateral triangle ideas are the arithmetic triangle and Sierpinski's gasket.  


And of course the second can be arrived by coloring in all the odd numbers in one color and the evens in another.   

Ok, How about a mathematical quadrilateral you never (probably) heard of, the equlic quadrilateral.  A quadrilateral ABCD such that AD and BC are of equal length, and angles A and B have a sum of 120 degrees.  

The two lower images show two relations of this shape with Equilateral triangles.  I an equilatera PCD is erected outside the quadrilateral, then PAB is also equilateral.   The bottom shows the midpoints of diagonals P, and Q, and the midpoint of CD will always form an equilateral triangle at all.  Toss "equalic quadrilateral" out at the next math dept meeting and rule the crew.  

Two non-associated pieces  not from the book, I'm writing this on November 7th and just printed up my post for On This Day in Math for November 8th, and it includes a note about the Death of Gino Fano on that date in 1952.  Fano's relation to the equilateral Triangle, of course, is his famous illustration of a finite geometry in which every line had three points and every point lies on three lines.  
One last hat tip to John D Cook who pointed out on LinkedIn a connection between the Fermat Primes and the Sierpinski Gasket.  If you've forgotten, the only Fermat numbers now known to be prime are  3, 5, 17, 257, and 65537.  You may also know that these numbers are related to what regular polygons are constructable by straight edge and compass.  Only numbers of the form  are constructable by classic geometry methods, where F is a product of distinct Fermat Primes .  

So that means there can only be values for F if we allow the empty set to be represented by 1, If you print out those values in binary, and he did, you get a perfect Gasket.  John aligned his on the left margin so his gasket is a right triangle, but it's the same beast.  
So go check out this book, especially if you are a student of geometry, a parent of a geometry student, or a teacher of geometry, or just like me, and you love looking at beautiful math.  And check out John Cook's blogsite as well.  
Oh, and you might drop back by this blog some time just to see that I'm staying busy and out of trouble.  

One application of equilateral triangles is the use of the Warren Truss.  The Warren Truss was designed in 1848 by James Warren and Willoughby Theobald Monzani. This truss consists of longitudinal members joined only by angled cross-members, forming alternately inverted equilateral triangle-shaped spaces along its length. One example of the use is in the new Bridge across the Tennessee River between Paducah and Ledbetter Kentucky on Hwy US 60.

How about some other ideas related to equilateral triangles and circles: 

One blog I follow regularly is Antonio Gutierrez's gogeometry.  If you teach/study/like plane geometry he should be one of your regular references.  

Recently among his posts have been a couple with a related theme, circles inscribed or circumscribed about an equilateral triangle.  I'm listing these because they are each a wonderful relationship, and together give these otherwise somewhat mundane seeming triangles a luster students?teachers/others might miss.  
I will post the problems, but not the proofs, which (if you can't/won't work them out yourself you can find at the links provided to Antonio's site.  

So on we go...
1)  draw a circle and inscribe an equilateral triangle. Now pick any point on the circumference and construct segments from this point to the three vertices.  The sum of the lengths of the two shorter segments will equal the third. The problem, and solution is here. 

2)  OK:  
Same triangle, same circle, but now we sum the square of the three distances ...????? and they sum to twice the square of a side of the equilateral triangle.  That proof is here.  


3)  And now one with the circle on the inside.  Again, from any point on the circle construct segments to the three vertices of the equilateral triangle.  Again the sum of the squares is related to a side length, but I'll let you chase that down for yourself.  Or you can go to the site here.  

Addendum: John Golden sent a comment with a link to a GeoGebra sketch showing all three.

And let's add one beautiful proof about infinite series that is approachable to clever students at the geometry level.  Analysis by elementary geometry.  Try it with your students.  



I have stated previously how much I like "napkin" techniques that give quick calculations or estimates of a problem. I also like things like visual displays which essentially prove some mathematical idea. The one at the top of the page is from the cover of Roger Nelsen's "Proofs without words II.." which is way too expensive for a paperback, but I will probably break down and buy it.

The problem, is that, except for mathematicians who already know the proof, it seldom convinces "without words". Most of my high school students will not look at this image and be able to explain easily and clearly why it shows that the limit as n goes to infinity of 1/4 + (1/4)2 + (1/4)3+ ... +(1/4)n is equal to 1/3. If I'm wrong, not generally, but in your particular case, then stay with me and read what's written, and tell me if you see it the way I do. The amazing thing in my experience, is that a question about analysis can be illustrated with simple plane geometry. 

I think they will be able to see that the triangle is divided into thirds... by the colors, 1/3 purple, 1/3 orange, 1/3 white. But I don't know if they can see the series of powers of 1/4 going off to infinity. That's why they have high school teachers... and so here are some words to help make it more "visual"
Look at the largest white triangle... can you see it is 1/4 of the largest (outside) triangle?... Ok, now look at the line across the top of the biggest white triangle, it connects the midpoints of two legs of an equilateral triangle, so the triangle above this medial segment, the one with multiple smaller triangles in it, is exactly congruent to the Biggest white triangle and is 1/4 of the total area of the outside triangle also. This upper triangle is a scale model of the original outside triangle,with all the same colors in the same positions and the white triangle in it is 1/4 of the area of this upper replica. So the second largest white triangle is 1/4 of the area of the Largest white triangle.... its area is 1/16 or (1/4) 2. Now the line above the second smallest white triangle is a medial segment of the upper triangle, and so the triangle above it, which is also a scale model of the original biggest triangle, is also 1/16 of the total area... and the third smallest white triangle, is 1/4 of that, so its area is 1/4 of 1/16 or (1/4)3... OK, now you see it, and as you move out each white triangle is 1/4 of the previous one... and sure enough, all the white triangles add up to 1/3 of the total area.

On This Day in Math - November 8

   



Algebra exists only for the elucidation of geometry.
~William Edge

The 312th day of the year; the number is expressed 2222 in base five. [It is also a Zuckerman number (a number that is divisible by the product of its digits) Thanks to David Brooks].

312 = 0!*5! + 1!*4! + 2!*3! + 3!*2! + 4!*1! + 5!*0! *Derek Orr

and 3122 is the sum of the cubes of the integers from 14 to 25. 3122=∑n=1425n3 *archimedes-lab.org

312 is between two twin primes 311 and 313.  Prime Curios points out that the next "see and say" number after 312 shares this quality, that is 131112 ("one three, one one, and one two") is between a pair of twin primes as well .
Patrick Honaker says this is the smallest such example.  



EVENTS

*Wik The library in 1566, drawn by John Bereblock and given to Queen Elizabeth I as part of a book when she first visited Oxford



1602 The Bodleian Library was established in Oxford, England. Whilst the Bodleian Library, in its current incarnation, has a continuous history dating back to 1602, its roots date back even further. The first purpose-built library known to have existed in Oxford was founded in the fourteenth century by Thomas Cobham, Bishop of Worcester. This small collection of chained books was situated above the north side of the University Church of St Mary the Virgin on the High Street. This collection continued to grow steadily, but when, between 1435 and 1437 Humphrey, Duke of Gloucester (brother of Henry V of England), donated a great collection of manuscripts, the space was deemed insufficient and a larger building was required. A suitable room was finally built above the Divinity School, and completed in 1488. This room continues to be known as Duke Humfrey’s Library.
The late sixteenth century saw the library go through a period of decline (to the extent that the library’s furniture was sold, and only three of the original books belonging to Duke Humfrey remained in the collection). It was not until 1598 that the library began to thrive once more, when Thomas Bodley (a former fellow of Merton College) wrote to the Vice Chancellor of the University offering to support the development of the library: "where there hath bin hertofore a publike library in Oxford: which you know is apparent by the rome it self remayning, and by your statute records I will take the charge and cost upon me, to reduce it again to his former use." Duke Humfrey’s Library was refitted, and Bodley donated a number of his own books to furnish it. The library was formally re-opened on 8 November 1602 under the name “Bodleian Library” (officially Bodley's Library) *Wik




1795   A letter from Miss Caroline Herschel to Sir Joseph Banks informs him that on the evening of the seventh she had observed a new comet.  "As the appearance of one of these objects is almost become a novelty,  I flatter myself that this intelligence will not be uninteresting to astronomers." *Phil. Trans. R. Soc. Lond. 1796 86, 131-134


On Nov 8 1824,  Gauss wrote to Franz Taurinus:
The assumption that the sum of the three angles of a triangle is less than 180° leads to a curious geometry, quite different from ours [i.e. Euclidean geometry] but thoroughly consistent, which I have developed to my entire satisfaction, so that I can solve every problem in it excepting the determination of a constant, which cannot be fixed a priori. .... the three angles of a triangle become as small as one wishes, if only the sides are taken large enough, yet the area of the triangle can never exceed, or even attain a certain limit, regardless of how great the sides are.

Franz Taurinus was a German mathematician best known for his work on non-Euclidean geometry.





1895 Wilhelm Conrad RÖNTGEN discovers x-rays. He followed his mentor August Kundt and became assistant at the University of Würzburg in 1872 (or 1871) but was not offered a post. He then worked at Strasbourg and Giessen, but returned in 1888 as Professor of Physics and Head of the Physikal Institut, then Rector of the University in 1894. There he discovered X-rays on the evening of Friday 8 Nov 1895 'at a late hour when assistants were no longer to be found in the laboratory'. He investigated the phenomenon in secret, taking an X-ray of his wife's hand, and first announced it in a paper, "Ein neue Art von Strahlen", to the Würzburg Physical-Medical-Society on 28 Dec and it appeared in their 1895 proceedings. By January he was famous. In the next year some 50 books and 1000 papers appeared on the subject! A journal devoted to the subject was founded in May 1896. The techniques of barium meals and enemas were developed in 1896. He left Würzburg for Munich in 1900, shortly before receiving the first Nobel Prize in Physics in 1901. He donated the prize money to the University of Würzburg. [Bowers. Darius, p. 48-49. Pengelley & Pengelley, pp. 155-157.] The Physikal Institut is at Röntgenring 8b and has a plaque on the outside. Röntgen's laboratory is now a modern physics laboratory, but the Institut has three display cases of memorabilia, including the X-ray of his wife's hand, his Nobel Prize certificate and a commendation from the German Physics Society, signed by Einstein and Planck. A lecture room that Röntgen used is preserved more or less as in his day. [Pengelley & Pengelley, pp. 158-159.]

1949 Claude Shannon's paper "Programming a Computer for Playing Chess", seminal in the development of computer chess and introducing the Shannon number is received by the Philosophical Magazine. It will be published in March of 1950. The Shannon number, named after Claude Shannon, is an estimated lower bound on the game-tree complexity of chess. Shannon calculated it as an aside in his 1950 paper



In 1980, scientists at the Jet Propulsion Laboratory in California announced the discovery of a 15th moon orbiting the planet Saturn, courtesy of Voyager I.*TIS

2011 An asteroid the size of an aircraft carrier, asteroid 2005 YU55, passes close by the Earth. OK, it will miss Earth by at least 201,700 miles, but in astronomical terms that distance is not great. The moon is further away from us than that.*Indiana Public Media Moment of Science



2018  An online auction closed for a motorised wheelchair (c.1988) used by Stephen Hawking. It was a lot listed by Christie’s with an initial estimate of £10,000 - £15,000. The sale was “offered to benefit the Stephen Hawking Foundation and the Motor Neurone Disease Association.” The price realized was £296,750. The wheelchair was notable as the earliest surviving example of one used by physicist Stephen Hawking. He used it from the end of the 1980s until early in the 1990s, before he became unable to use his hands on the control. BEC Mobility manufactured the wheelchair (serial number 440609) in England, with red and maroon leather. Motor modifications, were made as needed to improve its functionality.« *Tis 







BIRTHS


1656 Edmund Halley born. He is best known for his accurate prediction that the comet of 1682 would return in 1758. The BAYEUX TAPESTRY (Tapisserie de la Reine Mathilde) includes a clear picture of Halley's Comet.*VFR (Image at top is from a St Helena stamp commemorating the tercentennial of Halley's visit.)
He became professor of geometry at Oxford and was later appointed the second Astronomer Royal. After originating the question that prodded Newton to write the Principia, Halley edited and arranged the publication of this seminal work. Halley identified the proper motion of stars, studied the moon's motion and tides, realized that nebulae were clouds of luminous gas among the stars, and that the aurora was associated with the earth's magnetism. His prediction of the transit of Venus led to Cook's voyage to Tahiti.*TIS
Halley was buried in the graveyard of the old church of St. Margaret, Lee (in London). In the same vault is Astronomer Royal John Pond; the unmarked grave of Astronomer Royal Nathaniel Bliss is nearby. *Wik

The Tapestry at this time (2026) is in the British Museum and will later be at a museum in Reading while it's French home is being updated,

B J Pryor wrote :With the Bayeux Tapestry getting lots of attention, I have to share this. A month after the D-Day landings, the cover of the NEW YORKER display their own version of that tapestry. Instead of celebrating the invasion of England by Normandy, this one celebrated the invasion of Normandy by England (and others).
.







1843 Moritz Pasch (8 Nov 1843 in Breslau, Germany (now Wrocław, Poland)
- 20 Sept 1930 in Bad Homburg, Germany) mathematician who worked on the foundations of geometry. He found a number of assumptions in Euclid that nobody had noticed before. Pasch's analysis relating to the order of points on a line and in the plane is both striking and pertinent to its understanding. Every student can draw diagrams and see that if a point B is between A and a point C, then C is not between A and B, or that every line divides a plane into two parts. But no one before Pasch had laid a basis for dealing logically with such observations. These matters may have been considered too obvious; but the result of such neglect is the need to refer constantly to intuition, so that the logical status of what is being done cannot become clear. *SAU



1846 Eugenio Bertini (8 Nov 1846 in Forli, Italy - 24 Feb 1933 in Pisa, Italy) was an Italian mathematician who worked in projective and algebraic geometry. His work in algebraic geometry extended Cremona's work. He studied geometrical properties invariant under Cremona transformations and used the theory to resolve the singularities of a curve. A paper by Kleiman studies what the authors calls the two fundamental theorems of Bertini. These two fundamental theorems are among the ones most used in algebraic geometry. The first theorem is a statement about singular points of members of a pencil of hypersurfaces in an algebraic variety. The second theorem is about the irreducibility of a general member of a linear system of hypersurfaces. *SAU



1848 (Friedrich Ludwig) Gottlob Frege (8 Nov 1848; 26 July 1925) was a German mathematician and logician, founder of modern symbolic logic and first to put forward the view that mathematics is reducible to logic. He extended Boole's work by inventing logical symbols (symbols for "or"," if-then", etc.) that improved on the syllogistic logic it replaced. He also worked on general questions of philosophical logic and semantics. His theory of meaning, based on making a distinction between what a linguistic term refers to and what it expresses, is still influential. Frege tried to provide a rigorous foundation for mathematics on the basis of purely logical principles, but abandoned the attempt when Bertrand Russell, on whose work he had a profound influence, pointed out a paradox that made the system inconsistent. *TIS Frege's influence in the short term came through the work of Peano, Wittgenstein, Husserl, Carnap and Russell. In the longer term, however, Frege has become a major influence on the development of philosophical logic and the man who seems to have been largely ignored by his contemporaries has been avidly read by many in the second half of the twentieth century, particularly after his works were translated into English. *SAU



1854 Johannes Robert Rydberg (8 Nov 1854; 28 Dec 1919) Swedish physicist, known for the Rydberg constant in his empirical formula that related the wave numbers of the spectral lines of an element (1890). This formula expressed fundamental relationships in those lines, which he presumed were the result of the inner nature and structure of an element's atoms. In 1897, he suggested that an atomic number for each of the elements, rather than atomic weights, would be a better means for organizing the elements and their periodicity of their characteristics. His work did provided the basis for discovering the electron shell structure of the atom. It was later established that the integer number of positive charges on an element's nucleus (its number of protons) corresponded to his idea of atomic number. *TIS



1868 Felix Hausdorff (8 Nov 1868 in Breslau, Germany (now Wrocław, Poland)
- 26 Jan 1942 in Bonn, Germany) worked in topology creating a theory of topological and metric spaces. He also worked in set theory and introduced the concept of a partially ordered set.
As a Jew his position became more and more difficult. In 1941 he was scheduled to go to an internment camp but managed to avoid being sent.
Bonn University requested that the Hausdorffs be allowed to remain in their home and this was granted. By October 1941 they were forced to wear the "yellow star" and around the end of the year they were informed that they would be sent to Cologne.
They were not sent to Cologne but in January 1942 they were informed that they were to be interned in Endenich. Together with his wife and his wife's sister, he committed suicide on 26 January. He wrote to a friend on Sunday 25 January:
Dear Friend Wollstein
By the time you receive these lines, we three will have solved the problem in another way - in the way which you have continually attempted to dissuade us. ...
What has been done against the Jews in recent months arouses well-founded anxiety that we will no longer be allowed to experience a bearable situation. ...
Forgive us, that we still cause you trouble beyond death; I am convinced that you will do what you are able to do (and which perhaps is not very much). Forgive us also our desertion! We wish you and all our friends will experience better times
Yours faithfully
Felix Hausdorff
On the night of Sunday 25 January all three took barbiturates. Both Hausdorff and his wife Charlotte were dead by the morning of the 26 January. Edith, Charlotte's sister, survived for a few days in a coma before dying. *SAU
Example of non-integer dimensions. The first four iterations of the Koch curve, where after each iteration, all original line segments are replaced with four, each a self-similar copy that is 1/3 the length of the original. One formalism of the Hausdorff dimension uses the scale factor (S = 3) and the number of self-similar objects (N = 4) to calculate the dimension, D, after the first iteration to be D = (log N)/(log S) = (log 4)/(log 3) ≈ 1.26  *Wik  




1904 William Leonard Edge (8 Nov 1904 in Stockport, England - 27 Sept 1997 in Bonnyrigg, Scotland) graduated from Cambridge and lectured at Edinburgh University. He wrote many papers in Geometry. He became President of the EMS in 1944 and an honorary member in 1983. Edge wrote nearly 100 papers and his mastery of the area ranks him with Coxeter as one of the leading geometers of the 20th century. His work was a continuation of work started by the great geometers of the late 19th and early 20th centuries, in particular Castelnuovo, Cayley, Clebsch, Cremona, Fano, Fricke, Humbert, Klein, Plücker and Schläfli. Edge investigated a pencil of canonical curves of genus 6 on a del Pezzo quintic surface in a 5-dimensional projective space. He investigated the group of self-projectivities of the space, which is isomorphic to the symmetric group S5. He also used geometrical configurations to investigate groups and, although his work was out of fashion at a time when group theorists were moving towards the classification of finite simple groups, his work did provide a deeper understanding of some of these groups, for example Conway's simple groups. Edge was not someone uninterested in modern techniques, however, and it may come as a surprise to some that in a 1991 paper he included computer-drawn pictures.
Other topics Edge worked on, all of which exhibit his mastery of the subject, include nets of quadric surfaces, the geometry of the Veronese surface, Klein's quartic, Maschke's quartic surfaces, Kummer's quartic, the Kummer surface, Weddle surfaces, Fricke's octavic curve, the geometry of certain groups, finite planes and permutation representations of groups arising from geometry. *SAU



1914 George Bernard Dantzig (November 8, 1914 – May 13, 2005) was an American mathematical scientist who made important contributions to operations research, computer science, economics, and statistics.
Dantzig is known for his development of the simplex algorithm, an algorithm for solving linear programming problems, and his work with linear programming, some years after it was invented by the Soviet mathematician & economist Leonid Kantorovich. In statistics, Dantzig solved two open problems in statistical theory, which he had mistaken for homework after arriving late to a lecture of Jerzy Neyman.
Dantzig was the Professor Emeritus of Transportation Sciences and Professor of Operations Research and of Computer Science at Stanford.*TIS

Dantzing is known for the "accidental" solution of two unsolved problems which he mistook for homework.  






DEATHS


1633 Xu Guang-qi was a Chinese mathematician who made Western mathematics available by translating works into Chinese.*SAU

1703 John Wallis (3 Dec 1616- 8 Nov 1703) English mathematician. Wallis was skilled in cryptography and decoded Royalist messages for the Parliamentarians during the Civil War. Wallis was part of a group interested in natural and experimental science who started to meet in London. This group became the Royal Society (1663), with Wallis as a founder member and one of its first Fellows. He contributed substantially to the origins of calculus and was the most influential English mathematician before Newton. Wallis introduced our the symbol infinity for infinity (1656), and exponents using negative or fractional numbers (such as 1/x2 = x-2 or sqrt(x)=x^(1/2). In 1668, he was the first to suggest the law of conservation of momentum for colliding bodies, the first of all-important conservation laws.*TIS



1719 Michel Rolle, (21 April 1652 – 8 November 1719)whose favorite area of research was the theory of equations. He introduced the symbol we use for nth roots. *VFR (famous to Calculus I students for Rolle's Theorem... and I always tell my students he had a daughter named Tootsie) . He also deserves to be known as the co-inventor in Europe of Gaussian elimination.In 1690, Rolle published Traité d'Algebre. It contains the first published description in Europe of the Gaussian elimination algorithm, which Rolle called the method of substitution. *Wik

1858 George Peacock (9 Apr 1791 - 8 Nov 1858) English mathematician who, with fellow Cambridge undergraduates Charles Babbage and John Herschel brought reform to nomenclature in English mathematics. They formed the Analytical Society (1815) whose aims were to bring the advanced methods of calculus from Europe to Cambridge to replace the increasingly stagnant notation of Isaac Newton from the previous century. The Society produced a translation of a book of Lacroix in the differential and integral calculus. In 1830, he published Treatise on Algebra which attempted to give algebra a logical treatment, and which went at least partway toward the establishment of symbolic algebra. Instead of using only numbers he used objects, and showed the associativity and commutativity of these objects.*TIS
A really enjoyable book covering this development in English Mathematics is The Philosophical Breakfast Club: Four Remarkable Friends Who Transformed Science and Changed the World
, by Laura Snyder.



1952 Gino Fano (5 January 1871 – 8 November 1952) died in Verona, Italy. This geometer created a finite geometry that is now a common classroom example. *VFR  Fano worked on projective and algebraic geometry; the Fano postulate, Fano plane, Fano fibration, Fano surface, and Fano varieties are named for him. *Wik








1969 Vesto Melvin Slipher (11 Nov 1875, 8 Nov 1969) American astronomer whose systematic observations (1912-25) of the extraordinary radial velocities of spiral galaxies provided the first evidence supporting the expanding-universe theory. Died at Flagstaff, Ariz. *TIS
While at school at Indiana University, Slipher formed a personal bond with one of his professors, William Cogshall. Cogshall was one of the main reasons Slipher became interested in astronomy in the first place. Cogshall convinced Percival Lowell, director of the Lowell Observatory in Flagstaff, AZ, to take Vesto in as a temporary assistant. Slipher worked as an assistant from 1901 to 1915 when Lowell finally named him the assistant director of the observatory. One year later Percival Lowell died and Vesto became the acting director for the next ten years. In 1926, 25 years after arriving in Flagstaff, Slipher was named director of the Lowell Observatory. He remained in charge for 28 more years when he retired from professional life. Slipher spent his years there studying many things, but most notably, spectroscopy and redshifts of spiral nebulae. *Wik





2001 Albrecht Fröhlich (22 May 1916 – 8 November 2001) was a German mathematician who made important contributions to group theory*SAU  He was most well known for his major results and conjectures on Galois module theory in the Galois structure of rings of integers. *Wik



2004 Melba Newell Phillips (February 1, 1907 - November 8, 2004) was an American physicist and science educator. She completed her doctoral studies under J. Robert Oppenheimer and was also known for refusing to testify before a U.S. Senate Judiciary Committee's subcommittee on internal security, her actions leading to her dismissal by Brooklyn College. (Phillips appeared before a subcommittee hearing in New York and agreed to answer questions relating to her work as a scientist and physics educator, she invoked her Fifth Amendment rights when asked about other topics, including questions about whether she was a member of the Communist party.)
(In 1987 Brooklyn College publicly and personally apologized to Phillips for her dismissal from the College in 1952.)
Melba Phillips was born in Hazleton, Indiana. She graduated from high school at the age of 15 and went on to study Mathematics at Oakland City College, Indiana graduating in 1926. She received a master's degree in physics from Battle Creek College of Michigan in 1928 and her doctorate in physics in 1933 at the University of California, Berkeley.
Phillips's supervisor at Berkeley was J. Robert Oppenheimer, who would later become scientific head of the Allied atomic bomb effort, the Manhattan Project. Together they described the Oppenheimer-Phillips effect explaining the behavior of accelerated nuclei of radioactive hydrogen atoms in 1935. *Wik
*Wik



2009 Vitaly Lazarevich Ginzburg, ( October 4, 1916 – November 8, 2009) was a Soviet and Russian theoretical physicist, astrophysicist, Nobel laureate, a member of the Soviet and Russian Academies of Sciences and one of the fathers of Soviet hydrogen bomb. He was the successor to Igor Tamm as head of the Department of Theoretical Physics of the Academy's physics institute *Wik & *TIS




Credits :
*CHM=Computer History Museum
*FFF=Kane, Famous First Facts
*NSEC= NASA Solar Eclipse Calendar
*RMAT= The Renaissance Mathematicus, Thony Christie
*SAU=St Andrews Univ. Math History
*TIA = Today in Astronomy
*TIS= Today in Science History
*VFR = V Frederick Rickey, USMA
*Wik = Wikipedia
*WM = Women of Mathematics, Grinstein & Campbell