0,\; t.k.\; \frac{4\pi}{7}=\frac{4\cdot 180^0}{7}=\frac{720^0}{7}\approx 102,9^0\in 2\; chetvert\\\\cos(-\frac{5\pi}{7})<0,\. t.k.\; \frac{-5\pi}{7}=-\frac{900^0}{7}\approx -128,6^0\in 3\; chetverti\\\\sin\frac{9\pi}{8}<0,t.k.\; \frac{9\pi}{8}=\frac{1620^0}{8}=202,5^0\in 3\; chetverti\\\\sin\frac{-3\pi}{8}<0,t.k.\; \frac{-3\pi}{8}=\frac{-540^0}{8}=-67,5^0\in 4\; chetverti" alt="sin\frac{4\pi}{7}>0,\; t.k.\; \frac{4\pi}{7}=\frac{4\cdot 180^0}{7}=\frac{720^0}{7}\approx 102,9^0\in 2\; chetvert\\\\cos(-\frac{5\pi}{7})<0,\. t.k.\; \frac{-5\pi}{7}=-\frac{900^0}{7}\approx -128,6^0\in 3\; chetverti\\\\sin\frac{9\pi}{8}<0,t.k.\; \frac{9\pi}{8}=\frac{1620^0}{8}=202,5^0\in 3\; chetverti\\\\sin\frac{-3\pi}{8}<0,t.k.\; \frac{-3\pi}{8}=\frac{-540^0}{8}=-67,5^0\in 4\; chetverti" align="absmiddle" class="latex-formula">