Taking AB and AC of △ ABC as the sides, make square ABCD and ACGF outside the triangle, make an ⊥ BC at point n, extend Na and intersect EF at point m, and prove that EM = MF Square ABDE

Taking AB and AC of △ ABC as the sides, make square ABCD and ACGF outside the triangle, make an ⊥ BC at point n, extend Na and intersect EF at point m, and prove that EM = MF Square ABDE

Do EP ⊥ an at point P and FQ ⊥ an at point Q
According to △ AEP ≌ △ ABN, PE = an can be obtained
Similarly, FQ = an
∴PE=FQ
Further proof of △ PEM ≌ △ QFM
We can get me = MF