Question

Помогите упростить! (желательно поэтапно)
сos-cos*sin^{2}=
ctg^{2}-cos^{2}*ctg^{2}=

Answer 1

$cos alpha - cos alpha sin^2 alpha = cos alpha (1 - sin^2 alpha ) = cos alpha cos^2 alpha = cos^3 alpha \ ctg^2 alpha - cos^2 alpha ctg^2 alpha = ctg^2 alpha (1 - cos^2 alpha ) = dfrac{cos^2 alpha }{sin^2 alpha }sin^2 alpha = cos^2 alpha$