Cos² 2x=1+sin²2x сроочняяк

Question

Cos² 2x=1+sin²2x сроочняяк

Answer 1

Cos² 2x=1+sin² 2x
cos² 2x - sin² 2x=1
cos(2*2x)=1
cos 4x=1
4x=2πn, n∈Z
x=2πn/4, n∈Z
x=πn/2, n∈Z

Answer 2

Cos² 2x=1+sin²2x 

Cos² 2x=Cos² 2x+ sin²2x +sin²2x
 2sin²2x=0
2x=πn  n⊂Z
x=πn/2 n⊂Z