Question

упростите выражение (1-sin a)(1+sin a)/cos^2(-a)

Answer 1

$\frac{(1-Sin\alpha)(1+Sin\alpha)}{Cos^{2}(-\alpha)}=\frac{1-Sin^{2}\alpha}{Cos^{2}\alpha}=\frac{Cos^{2}\alpha}{Cos^{2}\alpha}=1$