How to Compute Area of Triangle (side side side)

You can compute the area of a triangle knowing the lengths of the sides and the measures of the angles. This article will show you how to calculate the area of a triangle just knowing the length of the 3 sides.

This method of finding the area of a triangle is known as the "side side side" formula, or Heron's formula.

Difficulty: Easy

Instructions

1. 
    

   As an example, let's use a triangle with side lengths 4, 5, and 7. The first step is the compute Z = (4 + 5 + 7)/2 = 8

2. The next step in finding the area of a triangle is to compute the product
   (Z)(Z-4)(Z-5)(Z-7) = (8)(4)(3)(1) = 96

3. The last step is to take the square root of the number you obtained in step two. Sqrt(96) = 9.8, so the area of the triangle is 9.8.

4. More generally, if the side lengths of the triangle are A, B, and C, then the area is Sqrt[Z(Z-A)(Z-B)(Z-C)], where Z = (A + B + C)/2.