The perimeter of an isosceles triangle is 21cm. Find the sides of the triangle if its pain side is 3cm

The perimeter of an isosceles triangle is 21cm. Find the sides of the triangle if its pain side is 3cm larger than the base.

An isosceles triangle is a triangle in which the sides are equal:

AB = BC.

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

P = AB + BC + AC.

Since the perimeter of the triangle is 21 cm, and its lateral side is 3 cm larger than its base, 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 = 21;

x + x + x = 21 – 3 – 3;

3x = 15;

x = 15/3 = 5;

AC = 5 cm;

AB = BC = 5 + 3 = 8 cm.

Answer: the length of the base of the AC is 5 cm, the length of the sides AB and BC is 8 cm.