Question

Найдите значение выражения: (2 sin(α − 7π) + cos ((-7π/2) + α) / (sin(α + π)). Вычислите: sin (arcsin (−√2/2) +arctg(−1)). Вычислите: sin (arcsin (-√2/2) + (−1)).

Answer 1

$1)\ \ \ \dfrac{2sin(a-7\pi )+cos(-\frac{7\pi}{2}+a)}{sin(a+\pi )}=\dfrac{-2sin(7\pi -a)+cos(\frac{7\pi}{2}-a)}{sin(\pi +a)}=\\\\\\=\dfrac{-2sina-sina}{-sina}=\dfrac{-3sina}{-sina}=3$

$2)\ \ sin\Big(arcsin(-\dfrac{\sqrt2}{2})+arctg(-1)\Big)=sin\Big(-arcsin\dfrac{\sqrt2}{2}-arctg1\Big)=\\\\\\=sin\Big(-\dfrac{\pi}{4}-\dfrac{\pi}{4}\Big)=sin\Big(-\dfrac{\pi}{2}\Big)=-sin\dfrac{\pi}{2}=-1$