How do you use Heron's formula to find the area of a triangle with sides of lengths #18 #, #9 #, and #13 #?
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
Now we simply plug in the values into Heron's formula
which is approximately 55.5