Question

2. The side of a triangle are in ratio 3:4:5 . if the parameter of a triangle is 84 cm, then the area of the triangle is
(a)274cm ^2
(b)294cm ^2
(c)290cm^2
(d)252cm^2




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Answer 1

Answer:

Correct option is

A

864 sq. cm

Given, Side of triangle are in ratio 3:4:5 and their perimeter 144 cm.

Let the sides of triangle be 3x,4x,5x

Perimeter =3x+4x+5x=144 cm

12x=144

∴x=12

Then sides of triangle are 3x=3×12=36 cm,

4x=4×12=48 cm,

5x=5×12=60 cm.

Now, Semi perimeter, s=

2

Sum of sides of triangle

=

2

36+48+60

=72 cm

Using Heron's formula, Area of triangle =

s(s−a)(s−b)(s−c)

=

72(72−36)(72−48)(72−60)

=

72×36×24×12

=864 cm

2