Question

Упростите выражение:
(1+cosα)*ctg²α*(1-cosα)

Answer 1

$(1+cos alpha )*ctg^{2} alpha *(1-cos alpha )=(1-cos^{2} alpha )*ctg^{2} alpha = \ sin^{2} alpha * frac{cos^{2} alpha }{sin^{2} alpha } =cos^{2} alpha$