The perimeter of an isosceles triangle is 19.8 cm. Find its sides if it is known that its side is 1.5 cm larger than the base.

Given: triangle ABC – isosceles
AB = BC = AC + 1.5 (cm)
P = 19.8 cm
Find: AB, BC, AC
Solution: Consider an isosceles triangle ABC: P = AB + BC + AC. Then
19.8 = AC + 1.5 + AC + 1.5 + AC;
19.8 = 3 * AC + 3;
19.8 – 3 = 3 * AC;
16.8 = 3 * AC;
AC = 16.8: 3;
AC = 5.6 centimeters;
5.6 + 1.5 = 7.1 centimeters – the length of the sides AB and BC.
Answer: 7.1 centimeters; 7.1 centimeters; 5.6 centimeters.