Question

Помогите!!
50 баллов!
$cos2x+sin ^{2}x=1$

Answer 1

cos²x-sin²x+sin²x=1
cos²x=1
(1+cos2x)/2=1
1+cos2x=2
cos2x=1
2x=2πn,n∈Z
x=πn,n∈Z