Question

The lengths of two sides of an isosceles triangle are 9 cm and 20 cm. What is the perimeter of the triangle?

Answer 1

The given triangle is an isosceles triangle. So, length of the third side would be either 9 cm or 20 cm.
But, the third side can’t be 9 cm, as the sum of two sides (9 cm + 9 cm = 18 cm) is not greater than the third side which is 20 cm.
Hence, the length of the third side will be 20 cm.
So, the perimeter of the triangle = 9 cm + 20 cm + 20 cm = 49 cm