Prove that : `cos^2 theta+ cos^2 ((2pi)/3 -theta) + cos^2 ((2pi)/3 +theta) = 3/2`

Prove that cos theta + cos ((2pi)/(3)- theta)+ cos ((2pi)/(3)+ theta)=0

Prove that: cos^(2)theta+cos^(2)((2 pi)/(3)-theta)+cos^(2)((2 pi)/(3)+theta)=(3)/(2)

Prove that: cos^(2)theta+cos^(2)((pi)/(3)+theta)+cos^(2)((pi)/(3)-theta)=(3)/(2)

Prove that cos theta +cos ((2pi)/(3)-theta)+cos ((2pi)/(3)+theta)=0

Prove that cos theta + cos[(2pi)/3 + theta] + cos [(4pi)/(3) + theta] = 0 .

Prove that: 2cos theta cos((pi)/(3)+theta)cos((pi)/(3)-theta)=cos3 theta

If cos^(3) theta + cos^(3)((2pi)/(3) + theta) + cos^(3)((4pi)/(3) + theta) = a cos 3 theta , then a =

the value of cos^(2)theta+cos^(2)((2 pi)/(3)-theta)+cos^(2)((2 pi)/(3)+theta) is (a) 3 (b) (1)/(2)(c)(3)/(2) (d)none of these

cos((3pi)/2+theta)=