Question

Обчислити суму: sin0+sin1+sin2+sin3++sin358+sin359+sin360

Answer 1

$\sin 0^\circ+\sin1^\circ+\sin2^\circ+...+\sin358^\circ+\sin359^\circ+\sin360^\circ=\\ \\ \\ =\Big(\sin0^\circ+\sin360^\circ\Big)+\Big(\sin1^\circ+\sin359^\circ\Big)+\Big(\sin2^\circ+\sin358^\circ\Big)+...=\\\\ \\ =2\sin\dfrac{360^\circ+0^\circ}{2}\cos\dfrac{360^\circ-0^\circ}{2}+2\sin\dfrac{359^\circ+1^\circ}{2}\cos\dfrac{359^\circ-1^\circ}{2}+\\ \\ \\ +2\sin\dfrac{358^\circ+2^\circ}{2}\cos\dfrac{358^\circ-2^\circ}{2}+...=2\sin180^\circ\cos180^\circ+\\ \\ \\ +2\sin180^\circ\cos179^\circ+2\sin180^\circ\cos178^\circ+...=0$

P.S. sin 180° = 0