Question

$\frac{ \sin ( 50 ) + \sin ( 10 ) }{ \cos ( 20 ) }$
Ответ 1,нужно решение ​

Answer 1

Ответ:

1

Объяснение:......................

$\[\begin{array}{l}a = ?\\\frac{{\sin (50\textdegree) + \sin (10\textdegree)}}{{\cos (20\textdegree)}} = a\\\sin (50\textdegree) + \sin (10\textdegree) = a\cos (20\textdegree)\\2\cos \frac{{50\textdegree - 10\textdegree}}{2}\sin \frac{{50\textdegree + 10\textdegree}}{2} = a\cos (20\textdegree)\\2\cos 20\textdegree\sin 30\textdegree = a\cos (20\textdegree)\\2\sin 30\textdegree = a\\2 \cdot \frac{1}{2} = a\\a = 1\end{array}\]$