Answer/Step-by-step explanation:
For ∆ABC and ∆DEF to be similar the following must be true:
1. ∠A ≅ ∠D
2. ∠B ≅ ∠E
3. ∠C ≅ ∠F
4. The ratio of the length of their corresponding sides must be equal and proportional.
That is:
![\frac{\overline{AB}}{\overline{DE}} = \frac{\overline{BC}}{\overline{EF}} = \frac{\overline{AC}}{\overline{DF}}](https://img.qammunity.org/2021/formulas/mathematics/high-school/yd0tjm0wx22pcl9cwr2bavu8h6811b9hk1.png)
If all these are true, then ∆ABC ~ ∆DEF, because the corresponding angles of two similar shapes are equal, while the ratio of their corresponding side lengths are equal.