Question

Решить 1-sin^2a/1-cos^2a = 1/tg^2a

Answer 1

$\frac{1-sin^2 \alpha }{1-cos^2 \alpha }=\frac{cos^2 \alpha }{sin^2 \alpha }=ctg^2 \alpha =\frac{1}{tg^2 \alpha}\\\\ (sin^2 \alpha +cos^2 \alpha =1\; \; \to \; \; 1-sin^2 \alpha =cos^2 \alpha ,\; \; 1-cos^2 \alpha =sin^2 \alpha ) }$