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

Prove that cos 8 theta cos 2 theta = cos^(2) 5theta- sin^(2) 3 theta

Prove that cos (pi + theta) = - cos theta

If veca, vecb and vecc are any three vectors forming a linearly independent system, then AA theta in R vecp=vecacostheta+vecbsintheta+vecc(cos2theta) vecq=vecacos((2pi)/(3)+theta)+vecbsin((2pi)/(3)+theta) + vecc(cos 2)((2pi)/(3)+theta) and vecr=vecacos(theta-(2pi)/(3))+vecbsin(theta-(2pi)/(3))+vecc cos2(theta-(2pi)/(3)) then [vecpvecqvecr]

Prove that cos 50 = 16 cos^(5)theta - 20 cos^(3) theta + 5 cos theta

If x cos theta = y cos (theta + (2pi)/(3)) = z cos (theta + (4pi)/(3)) , find the value of xy + yz + zx

Prove that (cot theta -cos theta )/( cot theta +cos theta ) =(cos ec theta -1)/( cosec theta +1)

Solve the equations: cos theta + cos 3theta = 2 cos 2theta

Prove that : (2 cos 2^n theta + 1)/(2 cos theta +1) = (2 cos theta -1) (2 cos 2theta -1) (2 cos 2^2 theta -1) … (2 cos 2^(n-1) theta -1)

The two legs of a right triangle are sin theta +sin ((3pi)/2-theta) and cos theta -cos( (3pi)/2-theta) The length of its hypotenuse is hypotenuse is

Prove that (sin theta+sin 2theta)/(1+cos theta+cos 2 theta)=tan theta