Solution:
As we know when two triangles are similar , their corresponding sides are proportional and Interior angles of two triangles are congruent.
So when, △DEF ~ △RST, There are following possibilities when they are similar
Corresponding interior angles of two triangles △DEF and △RST
1. ∠D=∠R
2. ∠E=∠S
3.∠F=∠T
Corresponding sides of △DEF and △RST
4.
