`cos4theta=cos2theta`

Solve the following equation: cos4 theta=cos2 theta

sin^2theta+cos^4theta=cos^2theta+sin^4theta

4cos6 theta cos4 theta cos2 theta=

Find the values of theta betwen 0^(@) and 180^(@) satisying the equation cos6 theta+cos4 theta+cos2 theta+1=0

If sin theta+sin^2theta=1 , show that cos^4theta+cos^2theta=1 .

Find the number of all values of theta in[0,10.5] satisfying the equation cos6 theta+cos4 theta+cos2 theta+1=0

(3+cos4 theta)cos2 theta=4(cos^(8)theta-sin^(8)theta)

Prove that (3 + cos 4theta) cos 2theta = 4(cos^(8)theta - sin^(8)theta) .

If tan^4theta+tan^2theta=1 , prove that, cos^4 theta+cos^2theta=1

If tan^4theta - tan^2 theta= 1 , then prove that cos^4theta+ cos^2theta = 1