Question

if cos
$if \: \cos {}^{2} \alpha - \sin^{2} \alpha = \frac{1}{x}$
then

cos​4​^4α−sin​^4α=?

Answer 1

take thetha as y,please, so lets go
$cos^4 y - sin^4 y = (cos^2 y - sin^2 y) (cos^2y+sin^2y) \\ sin^2y + cos^2y = 1\\ cos^4 y - sin^4 y = (cos^2 y - sin^2 y) = \frac{1}{x}$