Given that ΔABC and ΔDEF are two triangles such that

We know that AAA similarity criterion states that in two triangles, if corresponding angles are equal, then their corresponding sides are in the same ratio and hence the two triangles are similar.

⇒ ∠A = ∠D, ∠B = ∠E, ∠C = ∠F

∴ ΔCAB ~ ΔFDE

Hence proved.