Legendre who?

In Chapter 10 of my book, Euler’s Gem, I give Adrien-Marie Legendre‘s beautiful proof of Euler’s polyhedron formula: for any (convex) polyhedron with V vertices, E edges, and F faces, V-E+F=2. His use of spherical geometry to prove the theorem is extremely elegant. On page 88 I include the portrait of Legendre shown at right….