Solve `cos theta * cos 2 theta * cos 3 theta = (1)/( 4), 0 le theta le pi`

Solve cos theta+cos 3 theta-2 cos 2 theta=0 .

Solve cos theta+cos 2theta+cos 3theta=0 .

Solve : cos 6 theta + cos 4 theta + cos 2 theta + 1 = 0, 0^(@) lt theta lt 180^(@)

Solve: cos2theta=cos^(2)theta

Solve: sin 2 theta = cos 3 theta.

Solve sin^(2) theta-cos theta=1/4, 0 le theta le 2pi .

Find all the values of theta satisfying the equation cos 2 theta - cos 8 theta + cos 6 theta =1, such that 0 le theta le pi.

Solve sin 2 theta+cos theta=0 .

solve cos^(2)theta+cos theta=1

Solve: cos5theta=cos2theta