(sinx/tgx)^2+(cosx/ctgx)^2-sin^2x

Question

(sinx/tgx)^2+(cosx/ctgx)^2-sin^2x

Answer 1

(sinx/(sinx/cosx))^2+(cosx/(cosx/sinx)^2-sin^2x
cos^2x+sin^2x-sin^2x=cos^2x