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General

Easy

Question

# Find the area of a triangle, two sides of which are 18 cm and 10 cm and the perimeter is 42 cm.

Hint:

### Find third side using perimeter

## The correct answer is: 69.65 cm2

### Let third side be x

It is given that Perimeter of triangle = 42 cm

18 + 10 + x = 42

x = 42 – 28 = 14

So, length of third side is 14 cm

Using Heron’s formula,

Area of triangle = where s =

s = = 21

Area of triangle =

=

= 21 cm^{2}

( = 3.31)

= 69.65 cm^{2}

^{2}

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