well, for a right-triangle, we can use the congruence test for LL(leg leg), namely the legs of MN = NO and NP = NP, because of those two legs, we can say the triangles are congruent by LL, now, because the those legs are congruent, their hypotenuses must also be congruent, by the pythagorean theorem.
So we can say that because the legs of MN = NO and NP = NP, then MP = OP, and since MP = OP, we could use then the HL postulate to say that the triangles are congruent, this is allowed by the fact the legs MN = NO and NP = NP.
