Question

Докажите тождество:​

Answer 1

$frac{sin(alpha-pi )*cos(alpha-2pi )*sin(2pi -alpha)}{sin(90^{0} -alpha )*ctg(180^{0} -alpha )*ctg(270^{0} +alpha )} =frac{-sinalpha*cosalpha*(-sinalpha )}{cosalpha*(-ctgalpha )*(-tgalpha)} =sin^{2}alpha$

cos α сокращается;

(-ctg α) * (-tg α) = 1

(-sin α) * (-sin α) = sin²α