Question

Ctg^2b(cos^2b-1) упростите

Answer 1

$ctg ^{2}b(Cos ^{2} b - 1) = - frac{Cos ^{2} b}{Sin ^{2}b }*(1 - Cos ^{2}b) = - frac{Cos ^{2}b }{Sin ^{2}b }* Sin ^{2}b= - Cos ^{2}b$