how to prove it?

cos0= to 1/cos0 if u will divide it by will become cos squared .. so cos*cos=cos squared.
cot0 =cos/sin0 .. so sin0 divide with the cot0 it will change to multiplication ryt? so the same as above.. it will become sin squared/cot
in trigonometric derivation
cos squared is = to cos0cot0 and the sin squared/cot is = to tan0/csc0