Question

find the area of traingle two sides of which are 18cm and 10cm and the perimeter is 42cm

Answer 1

Here's ur required process..

Perimeter (p) = 42 cm
Semi Perimeter (s) =42/2 =21 cm
The three sides are 18, 10, (42-28 = 14) cm respectively..

So, area of the triangle (A) =
$\sqrt{s(s - a)(s - b)(s - c)} \\ = \sqrt{21(21 - 18)(21 - 14)(21 - 10)} \\ = \sqrt{3 \times 7 \times 3 \times 7 \times 11} = 3 \times 7 \sqrt{11} \\ = 21 \sqrt{11} sq \: \: units$
Hope this is ur required answer.
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