About This Tool
The Triangle Calculator computes area, perimeter, and all three angles of a triangle from its three side lengths using Heron's formula and the Law of Cosines.
Frequently Asked Questions
What is Heron's formula?
Heron's formula calculates triangle area from three side lengths: Area = √(s(s-a)(s-b)(s-c)) where s is the semi-perimeter.
What if my sides don't form a valid triangle?
The tool validates the triangle inequality rule — the sum of any two sides must be greater than the third. An error is shown for invalid triangles.
Are the angles shown in degrees?
Yes, all angles are displayed in degrees.