The perimeter of a triangle is 60 cm. If two of its side measure 15 cm and 20 cm respectively, find the third side.

Given:

Perimeter of triangle = 60 cm.

Two of its side measure 15 cm and 20 cm.

To find:

The third side of the triangle 

Solution:

Let the three sides be a, b, c.

a = 15 cm

b = 20 cm

c  = ?

Perimeter = Sum of all sides 

$60  =  a + b + c$

$60  =  15 + 20 + c$

$60  =  35  +  c$

$60 - 35  =  c$

$25  =  c$

$c  =  25$

So, the third side of the triangle is 25 cm.

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Updated on: 10-Oct-2022

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