7.2cos theta=x+(1)/(x)" zor alcos cestry "cos2 theta-3" ala? "

If 2cos theta=x+1/x then 2cos^2 theta=

If 2 cos theta = x + (1)/(x), prove that 2 cos 3 theta = x ^(3) + (1)/(x ^(3)).

If 2 cos theta=x+(1)/(x) , find the value of 2cos 3 theta

If theta=(pi)/(7), prove that cos theta cos2 theta cos3 theta=(1)/(2^(3))

If 2 cos theta=x+(1)/(x) and 2 cos phi=y+(1)/(y) then the value of cos (theta+phi) will be

if tan theta=(x)/(y) then sin2 theta+cos2 theta is

If cos2theta=x+1/x , prove that 2cos3theta=x^3+1/x^3

The roots of the equation |(3x^(2),x^(2) + x cos theta + cos^(2) theta ,x^(2) + x sin theta + sin^(2) theta),(x^(2) + x cos theta + cos^(2) theta,3 cos^(2) theta,1 + (sin 2 theta)/(2)),(x^(2) + x sin theta + sin^(2) theta,1 + (sin 2 theta)/(2),3 sin^(2) theta)| = 0