Question

Обчислити за формулою зведення
$\cos( - \frac{23\pi}{6} )$
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Answer 1

$cos(-\frac{23\pi}{6} )=cos(-\frac{24\pi-\pi}{6} )=cos(-(4\pi-\frac{\pi}{6}))=cos(\frac{\pi}{6}-2*2\pi)=cos(\frac{\pi}{6} )=\frac{\sqrt{3}}{2}$