Very the identity

Question

cos(x-y) / sin(x)sin(y) = cot(x)cot(y)+1

Answer 1

Let's VERIFY this (proposed) identity.  First, note that the denominator is the producrt sin x sin y, on left hand side.

Expanding the left hand side gives

cos x cos y + sin x sin y  ALL OVER sin x sin y; dividing gives us cot x cot y + 1 which is identical to the right hand side, so this identity is verified.