Question

Помогите решить.

 

$sinx*sin3x+sin4x*sin8x=0$

$1+ctgx - cos^2x=sin^2x$

$sin7x+cos^2 2x=sin^2 2x+sinx$

Answer 1

1+ctgx-cos^2x=sin^x;

1+ctgx-cos^2x=1-cos^2x:

ctgx=0 x=pi/2+2pik (k E Z)