Question

Вычислите:
а)
$\cos15\pi$
б)
$\sin \frac{25\pi}{2}$
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Answer 1

а)

$\cos(15\pi) = \cos( \pi + 2 \times 7\pi) = \cos(\pi) = - 1$

б)

$\sin( \frac{25\pi}{2} ) = \sin( \frac{\pi}{2} + 2 \times 6\pi ) = \sin( \frac{\pi}{2} ) = 1$