Find the area of the triangle if the length of the sides are 3, 8 and 9?

Given a triangle with know 3
sides.

We will use the formula of the area of a triangle
given the length of the sides.

==> A =
sqrt(s*(s-a)(s-b)(s-c) such that s is the perimeter/2 and a, b, and c are the length of
the sides.

Let us calculate the
perimeter.

==> p = 3+8+9 =
20

==> s = p/2 = 20/2 =
10

Let us
substitute.

==> A = sqrt(
10*(10-3)(10-8)(10-9)

==> A = sqrt( 10*7*2*1) =
sqrt140 = 2sqrt35

Then the area of the
triangle is 2sqrt35 = 11.83 square units.