Question

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

Answer 1

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