ГДЗ по геометрии 9 класс Мерзляк Задание 18

\[1)\ \frac{\sin{28{^\circ}}}{\sin{152{^\circ}}} = \frac{\sin{28{^\circ}}}{\sin(180{^\circ} - 28{^\circ})} =\]

\[= \frac{\sin{28{^\circ}}}{\sin{28{^\circ}}} = 1;\]

\[2)\ \frac{\cos{49{^\circ}}}{\cos{131{^\circ}}} = \frac{\cos{49{^\circ}}}{\cos(180{^\circ} - 49{^\circ})} =\]

\[= \frac{\cos{49{^\circ}}}{- \cos{49{^\circ}}} = - 1;\]

\[3)\ \frac{tg\ 12{^\circ}}{tg\ 168{^\circ}} = \frac{tg\ 12{^\circ}}{\text{tg}(180{^\circ} - 12{^\circ})} =\]

\[= \frac{tg\ 12{^\circ}}{- tg\ 12{^\circ}} = - 1;\]