If `cos^4theta-sin^4theta=2/3` then `2cos^2theta-1=`

If cos^2 theta-sin^2 theta= 1/2 then cos^4 theta-sin^4 theta=?

If cos^(4)theta-sin^(4)theta=(2)/(3) , then the value of 2cos^(2)theta-1 is

Prove the following identity : cos^4 theta- sin^4 theta= cos^2 theta-sin^2 theta= 2 cos^2 theta-1=1-2 sin^2 theta .

Prove the following: cos^4theta-sin^4theta+1=2cos^2theta

If cos^(4)theta-sin^(4)theta=(2)/(13) , find cos^(2)theta-sin^(2)theta+1 .

Prove the following sin^4theta-cos^4theta=sin^2theta-cos^2theta=1-2cos^2theta=2sin^2theta-1

Prove that sin^4theta-cos^4theta=sin^2theta-cos^2theta .

If sin theta + sin^(2) theta =1 then cos^(4) theta + cos^(8) theta + 2 cos^(6) theta =

The value of cos^4theta+sin^4theta-6cos^2theta is (a) cos2theta (b) sin2theta (c) cos4theta (d) none of these