Question

Упростить выражение:а)3(1-sin(a))(1+sin(a))/cos^2(-a)

Answer 1

$\displaystyle \frac{3(1-\sin\alpha)(1+\sin\alpha)}{\cos^2(-\alpha)} =\frac{3(1-\sin^2\alpha)}{\cos^2\alpha}=\frac{3\cos^2\alpha}{\cos^2\alpha}=3$