If `cos theta = 1/2 (a + 1/a),` show that `cos 2theta = 1/2 (a^2 + 1/a^2)`

If cos theta=(1)/(2)(a+(1)/(a)), show that cos2 theta=(1)/(2)*(a^(2)+(1)/(a^(2)))

If cos theta =(1)/(2)(a+(1)/(a)) , then cos 2 theta =

If cos theta=(1)/(2)(a+(1)/(a)) then show that cos3 theta=(1)/(2)(a^(3)+(1)/(a^(3)))

If theta = pi/(2^(n) + 1), "show that",2^(n) cos theta cos 2 theta cos2^(2) theta cos2^(3) theta.... cos2^(n-1) theta = 1.

If cos theta + (1)/(cos theta) = 4 , then prove that cos^(2) theta + (1)/(cos^(2)theta) = 14.

If cos theta + (1)/(cos theta) = 4 , then prove that cos^(2) theta + (1)/(cos^(2)theta) = 14.

If (sin theta + cos theta )=sqrt(2) cos theta , show that cot theta =(sqrt(2)+1).

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

IF 2 cos 4 theta + 9 cos 2 theta -7=0 , then show that , theta =(1)/(2) cos ^(-1)""(3)/(4)

If theta =(pi)/(2 ^(n) +1), then cos theta cos 2 theta cos 2^(2) theta …cos 2 ^(n-1)theta is equal to