Let PQ = 1 unit, QR = 2 units and PR = 3 units We know that the line joining the midpoints of two sides of a triangle is parallel to the third side and half of it. So, BC = 2DE = 2(2PQ) = 4PQ= 4 units Similarly, CA=4QR=4×2units=8units AB=4PR=4×3units=12units Therefore, perimeter of ΔABC =AB+BC+CA=12+4+8 =24 units