The two sides of the quadrangle are 36 cm long, and the third side is 2 times longer than the fourth.

The two sides of the quadrangle are 36 cm long, and the third side is 2 times longer than the fourth. The perimeter of the quadrilateral is 141 cm. Find the lengths of the third and fourth sides.

Let the length of the third side of the quadrangle be equal to X cm, then the length of its fourth side, by condition, is equal to X / 2 cm.

The perimeter of the quadrilateral is: 36 + 36 + X + X / 2 = 141.

1.5 * X = 141 – 72 = 69 cm.

X = 69 / 1.5 = 46 cm.

Then the four-sided side is 46/2 = 23 cm.

Answer: The dina of the third side is 46 cm, the length of the fourth side is 23 cm.