Q141 of 158 Page 159

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

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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