# The perimeter of an isosceles triangle is 30 cm, the lateral side is 3 cm longer than the base.

August 27, 2021 | education

| **The perimeter of an isosceles triangle is 30 cm, the lateral side is 3 cm longer than the base. What is the length of the base?**

An isosceles triangle is a triangle in which two sides are equal and are called lateral sides, and the third unequal is based:

AB = BC.

The perimeter of a triangle is the sum of all its sides:

P = AB + BC + AC.

Since the length of the lateral sides AB and Bc is 3 cm longer than the base of the AC, and the perimeter of the triangle is 30 cm, then we express:

x is the length of the base of the speaker;

x + 3 – the length of the sides AB and BC;

x + x + 3 + x + 3 = 30;

x + x + x = 30 – 3 – 3;

3x = 24;

x = 24/3 = 8;

AC = 8 cm;

AB = BC = 8 + 3 = 11 cm.

Answer: The length of the base of the speaker is 8 cm.

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