\[\boxed{\mathbf{1138}\mathbf{.}}\]
\[\sin^{2}a + \cos\left( \frac{\pi}{3} - a \right) \bullet\]
\[\bullet \cos\left( \frac{\pi}{3} + a \right) = \frac{1}{4}\]
\[\sin^{2}a + \frac{1}{2} \bullet\]