Question

Упростить
cos 39*cos 25+sin 39 * sin 25​

Answer 1

Ответ:

Cos39°cos25°+sin39°sin25°=cos(39°-25°)=cos14°

Answer 2

$\cos( \alpha - \beta )=$

$\cos( \alpha ) \cos( \beta ) + \sin( \alpha ) \sin( \beta )$

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$\cos(39) \times\cos(25)+ \sin(39)\times\sin(25)$=

$\cos(39 - 25) = \cos(14)$