Question

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

Answer 1

Sides of the isosceles triangle are 9 cm and 20 cm.

Since, the sum of any two sides of a triangle is greater than third side.

If the third side will be 9 cm then 9 + 9 = 18 < 20

So, the triangle will not form.

∴ Third side of triangle must be 20 cm.

Perimeter = (9 + 20 + 20) cm = 49 cm.