# How do you use Heron's formula to determine the area of a triangle with sides of that are 4, 7, and 8 units in length?

##### 1 Answer

Plug in your calculator...

#### Explanation:

Heron formula requires you know only the sides of a triangle to compute the area. Note you can use another approach i.e. determine the height of the triangle and use our familiar:

Where

There is an elegant prove to this leveraging trigonometry and using the following identities:

Try to complete the derivation...

You can also leverage "Pythagorean Theorem" on the following triangle... see image:

The idea is to express d and h only in terms of: