23 P_ABC-?

In a tangential triangle, the lengths of tangents from a vertex to the incircle are equal. Let AE = AF = 4, BE = BM = 10, and CM = CN = 6. The perimeter P_ABC = AB + BC + CA = (AE + EB) + (BM + MC) + (CN + NA) = (4 + 10) + (10 + 6) + (6 + 4) = 14 + 16 + 10 = 40.