Question

Докажите тождества (( sina-cosa)^2-1)/(sin^2a-cos^2a-1)×ctg (3п/2+a)=0

Answer 1

Объяснение:

$\frac{(sin\alpha -cos\alpha)^2-1 }{sin^2\alpha-cos^2\alpha -1 }+ctg(\frac{3\pi }{2}+\alpha ) =\frac{sin^2\alpha -2*sin\alpha *cos\alpha+cos^2\alpha-sin^2\alpha -cos^2\alpha }{sin^2\alpha-cos^2\alpha -sin^2\alpha -cos^2\alpha } -tg\alpha =\\=\frac{-2*sin\alpha*cos\alpha }{-2cos^2\alpha } =\frac{sin\alpha }{cos\alpha }-tg\alpha =tg\alpha -tg\alpha =0.$