,2.BF=EC，3。 ∠B=∠E，4。 ∠ 1=∠2。 Prove that all triangles ABC are equal to triangles DEF.

Proof: BF+FC=EC+FC because BF=EC.

So BC=EF

Also know. ∠B=∠E，4。 ∠ 1=∠2.

So triangle ABC is equal to triangle DEF(ASA)