We ask users to provide proof(s), reference(s) to proof(s), or further clarification on the proof(s) in this space.
: ratio of a circle's circumference to its diameter : http://dlmf.nist.gov/5.19.E4
: cosine function : http://dlmf.nist.gov/4.14#E2
: Euler's gamma function : http://dlmf.nist.gov/5.2#E1
We ask users to provide relevant URL links in this space.