Question

Cosa/ ctga
Ctg^2(2sin^2a+cos^2a-1)

Answer 1

Ответ:

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