Question

A 6.Докажи тождество: cos°

Answer 1

$\frac{ \cos(\pi + a) {}^{2} - \sin( \frac{\pi}{2} + a) {}^{2} - \cos(\pi - a) \cos(2\pi + a) }{ \tan( \frac{\pi}{2} + a) {}^{2} \cot( \frac{3\pi}{2} - a ) {}^{2} } = \frac{ \cos(a) {}^{2} - \cos(a) {}^{2} + \cos(a) \times \cos(a) }{ \tan(a) {}^{2} \times \cot(a) {}^{2} } = \cos(a) \times \cos(a) = \cos(a) {}^{2}$

cos²a=cos²a