\[1)\sin a = \frac{1}{2}:\]
\[0 < \frac{1}{2} < 1;\]
\[Ответ:\ \ да.\]
\[2)\sin a = 0,3:\]
\[0 < 0,3 < 1.\]
\[Ответ:\ \ да.\]
\[3)\cos a = \frac{\sqrt{3}}{5}:\]
\[0 < \frac{\sqrt{3}}{5} < 1.\]
\[Ответ:\ \ да.\]
\[4)\cos a = - 0,99:\]
\[- 1 < - 0,99 < 0.\]
\[Ответ:\ \ да.\]
\[5)\cos a = 1,001:\]
\[1,001 > 1.\]
\[Ответ:\ \ нет.\]
\[6)\sin a = \frac{\sqrt{5}}{2}:\]
\[\frac{\sqrt{5}}{2} = \frac{\sqrt{5}}{\sqrt{4}} > 1.\]
\[Ответ:\ \ нет.\]