Как решить (cos x-1)^2=cos^2 x-1

Question

Как решить
(cos x-1)^2=cos^2 x-1

Answer 1

(cos x-1)^2=(cos x-1)(cos x+1)
(cos x-1)*(cos x-1-cos x -1)=0
(cos x-1)*(-2)=0
cos x-1=0
cos x=1
x=2*pi*k