Heron's Formula for the area of a triangle(Hero's Formula)
A method for calculating the area of a triangle when you know the lengths of all three sides.
Let a,b,c be the lengths of the sides of a triangle. The area is given by:
where p is half the perimeter, or
Try this Drag the orange dots to reshape the triangle. The formula shown will re-calculate the triangle's area using Heron's Formula
Heron was one of the great mathematicians of antiquity and came up with this formula sometime in the first century BC,
although it may have been known earlier. He also extended it to the area of quadrilaterals and higher-order polygons.
Use the calculator on below to calculate the area of a triangle given 3 sides using Heron's formula.
Enter the three side lengths and press 'Calculate'. The area will be calculated.
Other triangle topics
Perimeter / Area
Congruence and Similarity
Triangle quizzes and exercises
(C) 2009 Copyright Math Open Reference. All rights reserved