17.`cos^4theta- sin^4theta` is equal to (a) 1 -2` sin^2(theta/2) ` (b)`2cos^2theta-1` (c)`1+2sin^2(theta/2)` (d)`1+2cos^2theta`

sin^(4) theta + 2 cos^(2) theta (1 - (1)/( sec^(2) theta)) + cos ^(4) theta =

sin^(4)theta+cos^(4)theta=1-2sin^(2)theta cos^(2)theta

Prove that : cos2 theta= cos^2 theta-sin^2 theta=1-2 sin^2 theta= 2 cos^2 theta-1 .

(sin ^ (4) theta + cos ^ (4) theta) / (1-2sin ^ (2) theta cos ^ (2) theta) = 1

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

Prove that sin^(4) theta + cos^(4) theta = 1 - 2 sin^2 theta cos^(2) theta

The value of (1-2 sin^2 theta cos^2 theta )/(sin^4 theta +cos^4 theta )-1 is: (1-2 sin^2 theta cos^2 theta )/(sin^4 theta +cos^4 theta )-1 का मान है :

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 that : sin^(4)theta + cos^(4)theta = 1 - 2 cos^(2) theta + 2 cos^(4)theta