[latex]42 \sqrt{6} cos \frac{ \pi }{4} cos \frac{5 \pi }{6} [/latex]

Question

[latex]42 \sqrt{6} cos \frac{ \pi }{4} cos \frac{5 \pi }{6} [/latex]

Алгебра

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Ответ(ы) на вопрос:

Accepted Answer

[latex]42 \sqrt{6} cos \frac{ \pi }{4} cos \frac{5 \pi }{6} =42\sqrt6*\frac{\sqrt2}{2}*(-\frac{\sqrt3}{2})=-63\\\\cos\frac{5\pi}{6}=cos(\frac{6\pi}{6}-\frac{\pi}{6})=cos(\pi-\frac{\pi}{6})=-cos\frac{\pi}{6}[/latex]