\[\boxed{\mathbf{1123}\mathbf{.}}\]
\[1)\ \frac{\sin\left( \frac{\pi}{4} + a \right) - \cos\left( \frac{\pi}{4} + a \right)}{\sin\left( \frac{\pi}{4} + a \right) + \cos\left( \frac{\pi}{4} + a \right)} =\]