Question

СРОЧНО! спростіть вираз (1+cos a)(1-cos a)-sin²a

Answer 1

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