Área triângulo (Heron)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The Heron triangle area calculator computes the area of a triangle when the lengths of all three sides are known. It uses Heron's formula: A = √[s(s−a)(s−b)(s−c)], where 's' is the semi-perimeter (s = (a + b + c)/2). This method is ideal when the height or internal angles of the triangle are unknown.
To use the calculator, input the lengths of the triangle's three sides. The tool automatically calculates the semi-perimeter and applies Heron's formula. The result is the area in square units corresponding to the input values. Ensure the sides form a valid triangle by verifying the triangle inequality theorem before using the calculator.
This tool is useful for geometry, engineering, and design projects. For instance, it helps calculate the area of triangular plots or irregular surfaces. Precautions include confirming that all side lengths are positive and satisfy the triangle inequality (a + b > c, a + c > b, b + c > a) for accurate results.
Frequently asked questions
How to ensure the input values form a valid triangle?
Check the triangle inequality theorem: the sum of any two sides must be greater than the third side (a + b > c, a + c > b, b + c > a).
Does the calculator work for right-angled triangles?
Yes, Heron's formula is valid for any triangle, including right-angled, isosceles, and scalene triangles.
What happens if one side is zero?
The formula returns zero, as a triangle must have three positive, non-degenerate sides (non-collinear).
Why use the semi-perimeter in the formula?
The semi-perimeter simplifies the calculation by expressing the area directly in terms of side lengths, without requiring heights or angles.