Given that in ΔABCandΔPQR,ABQR=BCPR=CAPQ.This shows that sides of one triangle are proportional to the sides of the other triangle. If the sides of one triangle are proportional to the sides of the other triangle, then their corresponding angles are also equal. So by SSS similarity rule, the given triangles are similar. i.e., ΔCAB∼ΔPQR