Question

sin^2a/1-sin^2a*ctg^2a

Answer 1

Ответ:

Объяснение:

sin²a/cos²a × (cosa/sina)²= 1

Answer 2

$\frac{Sin^{2}\alpha}{1-Sin^{2}\alpha}*Ctg^{2}\alpha=\frac{Sin^{2}\alpha}{Cos^{2}\alpha}*\frac{Cos^{2}\alpha}{Sin^{2}\alpha}=1$