# How do you use Heron's formula to find the area of a triangle with sides of lengths #18 #, #9 #, and #13 #?

##### 1 Answer

Feb 22, 2016

Heron's formula relates the area of a triangle to the side of the triangle

Where s is the sum of the side lengths divided by 2.

So, first we find s, the semiperimeter

So

Now we simply plug in the values into Heron's formula

which is approximately 55.5