| Heron's Formula Heron's formula enables you to calculate the area of a triangle from the lengths of its three sides. (For a method which uses two sides and the angle between them, see the Area of a Triangle page.) Start with a general triangle, with the angles labelled P, Q & R and the sides opposite them labelled p, q & r like this: 
Now define two new quantities "A" and "s":
Heron's formula states that: 
Historical note: named after the Greek mathematician and engineer Heron (or Hero). He didn't discover it (it had been known for centuries before he was born, somewhere around 20 CE) but he published a proof of it. Most recently updated at 18:30 (British time) on 07 April 2004 |