The perimeter of the triangle is 13cm. Its two sides are equal to each other, and the third side is 3cm.

The perimeter of the triangle is 13cm. Its two sides are equal to each other, and the third side is 3cm. Find the length of two equal sides of the triangle.

The perimeter of a triangle is found by the formula P = a + b + c, by the condition: a = 3, b = c. Subtract the length of the third side from the perimeter: 13-3 = 10 – the sum of two equal sides. Let’s denote the unknown side as x, the other is equal to it means – x, we get: x + x = 10, 2x = 10, x = 5 – length b, since b = c, then c = 5.