Explanation : The Context free grammar given over alphabets ∑{a, b, c} with S and T as non terminals are:
G1: S → aSb|T,T → cT|∈
G2: S → bSa|T,T → cT|∈
Lets L(G1) is the language for grammar G1 and L(G2) is the language for grammar G2
L(G1) = {ancmbn|n,m ≥ 0}
L(G2) = {bncman|n,m ≥ 0}
L(G1) ∩ L(G1) = {cman|m ≥ 0}; which is infinite and regular