Question

answer it according to the 9 th class.please fast​

Answer 1

Let the sides of the triangle be 6x, 7x and 8x respectively.

We know that,

Perimeter of a triangle = Sum of its sides

i.e,420=6x+7x+8x

i.e,420=21x

i.e,x=420/21=20

Now we have, x=20m

Thus sides of triangle are

6x=6x20=120m

7c=7x20=140m

8x=8x20=160m

Now, let us name that triangle as ABC

AB =120m

AC =140m

BC =160m

Let us draw AD (i.e,the height) perpendicular to side BC.

Then, D will be the mid point of that triangle.

BD =CD= 80m

With the help of Pythagoras Theorem,

(AD)^2 = (AC)^2 -(BC)^2=140^2-80^2= 19600-6400 =13200

AD=✓13200= 20✓33

Now,

Area of the triangle =1/2xbxh

=1/2xADxAC

=1/2x20✓33x80

=10✓33x80

=800✓33m^2