\[\boxed{\mathbf{1145}\mathbf{.}}\]
\[1)\arccos\frac{\sqrt{3}}{2} < \arccos\frac{1}{2}\]
\[\arccos\frac{\sqrt{3}}{2} = \frac{\pi}{6}\]
\[\arccos\frac{1}{2} = \frac{\pi}{3}\]
\[\frac{\pi}{6} < \frac{\pi}{3}\]
\[2)\arccos\left( - \frac{3}{4} \right) < \arccos( - 1)\]
\[\arccos\left( - \frac{3}{4} \right) = \pi - \arccos\frac{3}{4} < \pi\]
\[\arccos( - 1) = \pi - \arccos 1 =\]
\[= \pi - 0 = \pi\]
\[\arccos\left( - \frac{3}{4} \right) < \arccos( - 1)\]
\[3)\arccos\left( - \frac{\sqrt{2}}{2} \right) > \arccos\left( - \frac{1}{2} \right)\]
\[\arccos\left( - \frac{\sqrt{2}}{2} \right) = \pi -\]
\[- \arccos\frac{\sqrt{2}}{2} = \pi - \frac{\pi}{4} = \frac{3\pi}{4}\]
\[\arccos\left( - \frac{1}{2} \right) = \pi - \arccos\frac{1}{2} =\]
\[= \pi - \frac{\pi}{3} = \frac{2\pi}{3}\]
\[\frac{3\pi}{4} > \frac{2\pi}{3}\]