The perimeter of the triangle is 60 cm, while the lengths of the sides of the triangle form an arithmetic

The perimeter of the triangle is 60 cm, while the lengths of the sides of the triangle form an arithmetic progression, the difference of which is 9 cm. Find the lengths of the sides of this triangle.

The perimeter of a triangle is equal to the sum of the lengths of its sides:

P = a + b + c;

Let a =х, then b = x + 9, a c = x + 9 + 9. Make the equation:

x + x + 9 + x + 9 + 9 = 60;

3x + 27 = 60;

x + 9 = 20;

x = 20 – 9;

x = 11 cm.

a = 11 cm, b = 20 cm, c = 29 cm.

Answer: 11 cm, 20 cm, 29 cm.