Question

упростите:

sin3π/10 - sin7π/10​

Answer 1

Ответ: 0

Объяснение:

1 способ

$\sin(\frac{3\pi}{10} )-\sin(\frac{7\pi}{10} )=2\sin(\frac{\frac{3\pi}{10}-\frac{7\pi}{10}}{2})\cdot \cos(\frac{\frac{3\pi}{10}+\frac{7\pi}{10}}{2})=\\=2\sin(-\frac{2\pi}{10})\cdot \cos(\frac{\pi}{2})=2\sin(-\frac{\pi}{5})\cdot 0 = 0$

2 способ

$\sin(\frac{3\pi}{10})-\sin(\frac{7\pi}{10})=\sin(\frac{3\pi}{10})-\sin(\pi -\frac{3\pi}{10})=\sin(\frac{3\pi}{10}) - \sin(\frac{3\pi}{10})=0$