Respuesta :
From the given information,
B and C are extreme angles of BC and N and M are extreme angles of NM.
Also, it is given that B = N and C = M (= 90°) and BC ≅ NM.
With these details, Nessa used ASA congruent and proved that the triangles are congruent.
If we compare these statements with Roberto's proof,
AB ≅ QN is seen as an additional statement.
It seems that Roberto would miss the information BC ≅ NM. Otherwise, he also would go with ASA rule.
So, Roberto considered the statements B = N, C = M and AB ≅ QN and hence he opted AAS rule.