\[1)\sin\frac{7\pi}{10}\ и\ \sin\frac{13\pi}{10}\]
\[\frac{\pi}{2} < \frac{7\pi}{10} < \frac{13\pi}{10} < \frac{3\pi}{2}\]
\[\sin\frac{7\pi}{10} > \sin\frac{13\pi}{10}.\]
\[2)\sin\frac{13\pi}{7}\ и\ \sin\frac{11\pi}{7}\]
\[\frac{3\pi}{2} < \frac{11\pi}{7} < \frac{13\pi}{7} < \frac{5\pi}{2}\]
\[\sin\frac{13\pi}{7} > \sin\frac{11\pi}{7}.\]
\[3)\sin\left( - \frac{8\pi}{7} \right)\ и\ \sin\left( - \frac{9\pi}{8} \right)\]
\[- \frac{3\pi}{2} < - \frac{8\pi}{7} < - \frac{9\pi}{8} < - \frac{\pi}{2}\]
\[\sin\left( - \frac{8\pi}{7} \right) > \sin\left( - \frac{9\pi}{8} \right).\]
\[4)\sin 7\ и\ \sin 6\]
\[\frac{3\pi}{2} < 6 < 7 < \frac{5\pi}{2}\]
\[\sin 7 > \sin 6.\]