As shown in the figure, there are two intersecting line segments Mn, EF in square ABCD, m, N, e, f on edge AB, CD, ad, BC respectively. Student a thinks: if Mn = EF, then Mn ⊥ EF; student B thinks: if Mn ⊥ EF, then Mn = ef. Do you think () A. Neither is right. B. both are right. C. only a is right. D. only B is right

As shown in the figure, there are two intersecting line segments Mn, EF in square ABCD, m, N, e, f on edge AB, CD, ad, BC respectively. Student a thinks: if Mn = EF, then Mn ⊥ EF; student B thinks: if Mn ⊥ EF, then Mn = ef. Do you think () A. Neither is right. B. both are right. C. only a is right. D. only B is right

As shown in the figure, let e be eg ⊥ BC at point G, m be MP ⊥ CD at point P, let EF and Mn intersect at point O, MP and EF intersect at point Q, ∵ quadrilateral ABCD is a square, ∵ eg = MP, in the case of RT △ EFG and RT △ MNP, Mn = efeg = MP, ≌ RT △ EFG ≌ RT △ MNP (HL), ≌ MNP =