2. Where: ∠ 1 and ∠A are the ipsilateral internal angles obtained by cutting straight line DE by straight line AB and straight line AC. At this time, the three lines form an angle of 12. At this time, the congruence angles ∠ 1 and ∠8, ∠2 and ∠5, ∠3 and ∠6, ∠4 and ∠7, and the internal angles ∠4 and ∠5.

3. Where: ∠ 5 and ∠A are ipsilateral internal angles obtained by cutting straight line AB and straight line DE by straight line AC. At this time, the three lines form an angle of 12. At this point, the congruence angle is the same as above, and the internal angle is the same as above.