We provide a proof of Euler’s sine product formula using simple techniques of calculus and illustrate how our method can be used to prove similar product formulas for cosine as well as hyperbolic sine ...

Some are about famous unsolved problems, others are about notable numbers such as zero, π or e, and still others, including Dr Euler's Fabulous Formula by Paul Nahin, are about important equations.

A stretch too far, perhaps, but Nahin’s tale of the formula ei π + 1 = 0, which links five of the most important numbers in mathematics, is remarkable.