Question

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1/ Вычисли cost и sint, если t равно: − 8π3.
2/ 2сtgπ4−23tg2(−π3) =

Answer 1

Ответ:

1.

$\cos( - \frac{8\pi}{3} ) = \cos( - 2\pi - \frac{2\pi}{3} ) = \\ = \cos( - \frac{2\pi}{3} ) = \frac{1}{2} \\ \sin( - \frac{8\pi}{3} ) = \sin( - \frac{2\pi}{3} ) = - \frac{ \sqrt{3} }{2}$

2.

$2ctg( \frac{\pi}{4} ) - 23tg( - \frac{\pi}{3} ) = 2 \times 1 - 23 \times \frac{ \sin( - \frac{\pi}{3} ) }{ \cos( - \frac{\pi}{3} ) } = \\ = 2 - 23\times \frac{ - \frac{ \sqrt{3} }{2} }{ \frac{1}{2} } = 2 - 23 \times ( - \frac{ \sqrt{3} }{2} \times 2) = 2 + 23 \sqrt{3}$