- Prove: C-2 as an activity.
- Given: ABC ~ RST; DEF ~ RST
- To Prove: ABC ~ DEF

Choose from these possible answers:
* ΔABC ~ ΔRST; ΔDEF ~ ΔRST
* ∠A = ∠R, ∠D = ∠R; ∠C = ∠T, ∠F = ∠T
* ∠A = ∠D, ∠C = ∠F
* ΔABC ~ ΔDEF
* ΔRST ~ ΔDEF
* AA
* Given
* Definition of a Δ
* Definition of ~ Δ's