Question

2cos²x = 1
HELP ME))))

Answer 1

2 * cos² x = 1 
cos² x = 1/2 
cos x = - sqr (1/2)
cos x = sqr (1/2) 
cos x = - sqr (2) / 2
cos x = sqr (2) / 2 
x = 3pi/4
x = 5pi/4
x = 7pi/4
x = pi/4 

omвеm: 
pi/4 ; 3pi/4 ; 5pi/4 ; 7pi/4