Find the real zeros of the trigonometric function on the int

Find the real zeros of the trigonometric function on the interval 0 Inequality Theta

f(x)=sin2x -cosx

sin2x -cosx =0

2sinxcosx -cosx =0

cosx(2sinx -1)=0

cosx =0 ,2sinx -1 =0

cosx =0,sinx =1/2

cosx =0 =>x =pi/2, 3pi/2

sinx=1/2 =>x =pi/6,5pi/6

therefore x=pi/6,pi/2,5pi/6, 3pi/2 are solutions