3)

The triangle has angles $$135^\circ$$, $$45^\circ$$, and $$180^\circ - 135^\circ - 45^\circ = 0^\circ$$, which is impossible. Assuming the $$135^\circ$$ is an exterior angle, the interior angle is $$45^\circ$$. The triangle is right-angled isosceles. $$y = 3$$ m.