Question

If sides of triangle are in the ratio 13:14:15 and its perimeter is 84 cm find area

Answer 1

lets take P as the perimeter
From the question,
let's take a = 13x, b = 14x, c = 15x

since,
$p \: = \: a + b + c$
84 = 13x + 14x +15x
84 = 42x
2 = x

From the above value of x, the sides are
a = 13x = 13(2) = 26
b = 14x = 14(2) = 28
c = 15x = 15(2) = 30

now herons formula,
$area \: = \: \sqrt{s(s - a)(s - b)(s - c)}$
and here s is semi perimeter,

$s = (a + b + c) \div 2$
Now you have everything to find the area. I hope you will find it yourself.

Have a great day.