: While the problems are deep, they are framed so they don't strictly require calculus, though they remain "very challenging" for many undergraduate students.
: Unlike recreational puzzle books, Dörrie provides rigorous, unabridged mathematical proofs for every single entry. 100 great problems of elementary mathematics: t...
: Covers the five regular solids and the sphere circumscribing a tetrahedron. : While the problems are deep, they are