`1+ cos 2 theta + cos 4 theta + cos 6 theta = `

4 cos 6 theta cos 4 theta cos 2 theta =

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

1 + (cos 2 theta + cos 6 theta)/(cos 4 theta) = (sin 3 theta)/(sin theta).

4cos6 theta cos4 theta cos2 theta=

( cos 6 theta +6 cos 4 theta + 15 cos 2 theta + 10)/( cos 5 theta + 5 cos 3 theta + 10 cos theta)=

Prove the following : cos 7 theta + cos 5 theta + cos 3 theta +cos theta =4 cos theta cos2 theta cos4 theta for all value of theta .

1+cos2 theta+cos4 theta+cos6 theta=

Prove the following : cos 3 theta+ cos 5 theta+ cos 7 theta+ cos 9 theta= 4 cos theta cos 2 theta cos 6 theta .

Show that ((cos theta - cos 3theta)(sin 8theta + sin 2 theta))/((sin 5 theta - sin theta)(cos 4 theta - cos 6 theta)) = 1

If 0 le theta le pr, cos 6theta + cos 4theta + cos 2theta + 1 =0 then the ascending order of the values of theta is