Question

Tg^2альфа * cos^2афльфа + ctg^2альфа * sin^2альфа

Answer 1

$\tan {}^{2} ( \alpha ) \times \cos {}^{2} ( \alpha ) + \cot {}^{2} ( \alpha ) \times \sin {}^{2} ( \alpha ) = \\ = \sin {}^{2} ( \alpha ) + \cos {}^{2} ( \alpha ) = 1$