Q. 141

# 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 :

**Formula Used/Theory:-**

Perimeter = sum of all sides of triangle

There can be 2 cases

(i) If equal sides in isosceles triangle is equal to 9cm

Then;

Perimeter = 9cm + 9cm + 20cm

= 38cm

(ii) If equal sides in isosceles triangle is equal to 20cm

Then;

Perimeter = 20cm + 20cm + 9cm

= 49cm

∴ perimeter of triangle can be either 38cm or 49cm

**Result:-** Perimeter of triangle is either 38cm or 49cm.

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