The perimeter of the quadrilateral is 38cm, the length of one of its sides is 11cm

The perimeter of the quadrilateral is 38cm, the length of one of its sides is 11cm, the second is 7cm, and the other two sides are equal. Find the unknown sides of the quadrilateral.

The perimeter of a quadrilateral is equal to the sum of all its sides. Since we know two sides, and the other two sides are equal, we denote the third side by x, by the hypothesis of the problem, the fourth side is also equal to x. Let’s write expressions for finding the perimeter of a quadrangle: P = a + b + c + d. Substitute our values: 38 = 11 + 7 + x + x. Let’s solve the resulting equation: 2x = 38 – 11 – 7, 2x = 20, x = 20: 2, x = 10. the third and fourth sides are equal to 10 cm. Answer: the unknown sides are equal to 10 cm.