Question

Докажите тождество. 1 - cos^2(a) - sin^2(a) = 0

Answer 1

Ответ:

$1 - \cos ^{2} ( \alpha ) - \sin ^{2} ( \alpha ) = \\ = 1 - ( { \sin}^{2} (\alpha ) + { \cos}^{2} (\alpha )) = 1 - 1 = 0$