Question

Find the area of a triangle whose sides are 3 cm, 4 cm and 5 cm respectively.

 

Answer 1

The area of a triangle having sides a, b, c and s as semi-perimeter is given by,

`A = sqrt( s(s-a)(s-b)(s-c)`, where

`s = (a+b+c)/2`
Therefore the area of a triangle, say having sides 3 cm, 4 cm and 5 cm is given by

a = 3 cm ; b = 4 cm ; c = 5 cm

`s = (a+b+c)/2`

`s = (3+4+5)/2`

`s =12/2`

s = 6 cm Now, area `A = sqrt(s(s-a)(s-b)(s-c)`

\[= \sqrt{6(6 - 3)(6 - 4)(6 - 5)}\]
\[ = \sqrt{6 \times 3 \times 2 \times 1}\]
\[ = \sqrt{36}\]
\[ = 6 c m^2\]