Упростите выражение tgx*ctgx-cos^2x

Question

Упростите выражение tgx*ctgx-cos^2x

Answer 1

Tgx*ctgx-cos²x=1-cos²x=sin²x=(1-cosx)(1+cosx)

Answer 2

Tgx*ctgx = 1

1 - cos^2(x) = sin^2(x)

================================================