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Find the area of a triangle whose sides are 9 cm, 12 cm and 15 cm ?

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#### Solution

The triangle whose sides are a = 9cm, b = 12 cm and c = 15 cm

The area of a triangle `=sqrt(s(s-a)(s-b)(s-c))`

Here 1s = semi-perimeter of a triangle

`2s = a + b + c`

`s=(a+b+c)/2=(9+12+15)/2=(36)/2=18cm`

∴ area of a triangle= `sqrt(s(s-a)(s-b)(s-c))`

`=sqrt(18(18-9)(18-12)(18-15))=sqrt(18(9)(6)(3))`

`=sqrt(18cm xx3cmxx54cm^2) =54cm^2`

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