(cosx)(cscx) = cotx
cscx = 1/sinx
(cosx)(1/sinx) = (cosx/sinx)
cosx/sinx = cotx
Basically, I noticed that cscx is equivalent to 1 divided by sinx, and then multiplied that fraction by cosx, which got me cosx/sinx. Your quotient identities will tell you that cosx/sinx = cotx