\[\boxed{\mathbf{442.}}\]
\[1)\ a = \frac{\pi}{6}\]
\[0 < \frac{\pi}{6} < \frac{\pi}{2}\]
\[в\ I\ четверти.\]
\[2)\ a = \frac{3\pi}{4}\]
\[\frac{\pi}{2} < \frac{3\pi}{4} < \pi\]
\[\ во\text{\ II\ }четверти.\]
\[3)\ a = - \frac{3\pi}{4}\]
\[2\pi - \frac{3\pi}{4} = \frac{8\pi}{4} - \frac{3\pi}{4} = \frac{5\pi}{4}\]
\[\pi < \frac{5\pi}{4} < \frac{3\pi}{2}\]
\[в\ III\ четверти.\]
\[4)\ a = \frac{7\pi}{6}\]
\[\pi < \frac{7\pi}{6} < \frac{3\pi}{2}\]
\[в\ III\ четверти.\]
\[5)\ a = - \frac{7\pi}{6}\]
\[2\pi - \frac{7\pi}{6} = \frac{12\pi}{6} - \frac{7\pi}{6} = \frac{5\pi}{6}\]
\[\frac{\pi}{2} < \frac{5\pi}{6} < \pi\]
\[во\text{\ II\ }четверти.\]
\[6)\ a = 4,8\]
\[\pi \approx 3,14\]
\[1,5\pi < 4,8 < 2\pi\]
\[в\ IV\ четверти.\]
\[7)\ a = - 1,31\]
\[\pi \approx 3,14\]
\[2\pi - 1,31 \approx 6,28 - 1,31 \approx 4,97\]
\[1,5\pi < 4,97 < 2\pi\]
\[в\ \text{IV\ }четверти.\]
\[8)\ a = - 2,7\]
\[\pi \approx 3,14\]
\[2\pi - 2,7 \approx 6,28 - 2,7 \approx 3,58\]
\[\pi < 3,58 < 1,5\pi\]
\[в\ III\ четверти.\]