4)

The triangle has angles $$135^\circ$$, $$90^\circ$$, and $$180^\circ - 135^\circ - 90^\circ = -45^\circ$$, which is impossible. Assuming the $$135^\circ$$ is an exterior angle, the interior angle is $$45^\circ$$. The triangle is right-angled isosceles. $$y = 19$$ cm.