## \$bm²+cn²=mn²\$ in a problem

Known Information: $$△ ABC$$ rectangular isoscel $$M$$, $$N$$ belong to hypotenuse angle measurement $$\angle MAN = 45^\circ$$ Requirement: to demonstrate that $$BM^2 + CN^2 = MN^2$$.

Is a good idea to start using The generalized Pythagoras theorem?