упростите выражение: cos^2t-(ctg^2t + 1) * sin^2 t

Question

упростите выражение:

cos^2t-(ctg^2t + 1) * sin^2 t

Answer 1

Cos^2t-(Ctg^2+1)*Sin^2t=Cos^t-(Sin^2t/Sin^2t)=Cos^2t

Answer 2

cos^2t-(ctg^2t + 1) * sin^2 t  =  cos^2t - 1/sin^2t * sin^2t = cos^2t - 1 =  -(1-cos^2t) = -sin^2t