Given that lines \(M\) and \(N\) are parallel and angle \(1\) measures \(135^\circ\), we can determine the measure of angle \(8\) using the properties of parallel lines and transversals.
Angle \(1\) and angle \(8\) are corresponding angles because they are formed by the same transversal and are in corresponding positions relative to the parallel lines \(M\) and \(N\). For parallel lines cut by a transversal, corresponding angles are equal.
Since angle \(1\) measures \(135^\circ\):
\[ \text{Angle } 8 = \text{Angle } 1 = 135^\circ \]
Thus, the measure of angle \(8\) is \(135^\circ\).