Question 365339
cot^2x-cos^2x= cot^2xcos^2x
Change to sines and cosines
(cos^2/sin^2) - cos^2 = (cos^2/sin^2)*cos^2
Divide by cos^2
(1/sin^2) - 1 = cos^2/sin^2
Multiply by sin^2
1 - sin^2 = cos^2