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

Question

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

Answer 1

 

Answer 2

ctg^2(t)=cos^2(t)/sin^2(t);

раскрываем скобки, получаем: cos^2(t) - cos^2(t) - sin^2(t) = -sin^2(t).

Ответ: -sin^2(t).