A triangle calculator computes the area, perimeter, and all three angles of a triangle from the three side lengths.
About this calculator
A triangle calculator computes the area, perimeter, and all three angles of a triangle from the three side lengths. It uses Heron's formula for area (√(s(s−a)(s−b)(s−c)) where s is the semi-perimeter) and the law of cosines for angles.
Triangle calculations come up in geometry, construction, navigation, engineering, and physics. Any polygon can be divided into triangles, so triangle math ends up being widely applicable.
Common uses
- Calculate the area of a triangular land plot
- Find all angles of a triangle from three measured side lengths
- Verify a triangle is right-angled (using the Pythagorean theorem)
- Compute the perimeter for fencing or framing purposes
Frequently asked questions
What is Heron's formula for triangle area?
Heron's formula: Area = √(s(s−a)(s−b)(s−c)), where a, b, c are side lengths and s = (a+b+c)/2 is the semi-perimeter. It requires only the three side lengths and no angles or heights.