Question

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

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