Which congruence theorem can be used to prove △abr ≅ △acr

The
according to the figure, the sides of the two triangles △ABR and △ACR  have specific congruence. 
the congruences are:
AB≅ BC and AR ≅ CR, these mean that the sides are proportional

such triangles are called similar

so  to prove that △ABR ≅ △ACR , we can use SSS theorem
side-side -side Similarity theorem