Let the second side length be x; then first side length is 2x and third side length is (x+8). From the problem, you have this equation x + 2x + (x+8) = 72. Its solution is x= 16 cm. So, first side length is 32 cm; second side length is 16 cm and third side length is 24 cm. The triangle inequalities are satisfied, so the obtained numbers provide the ANSWER.
Firstside 2d Secondside d Thirdside d+8 PERIMETER 72