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Area, perimeter and sides of a triangle.
The Triangle Calculator finds the area of a triangle two ways: from a base and its perpendicular height, or from the lengths of all three sides using Heron's formula.
When you enter three sides it also checks the triangle inequality (each side must be shorter than the sum of the other two) and returns the perimeter, so you know whether the triangle can exist at all.
Heron's formula needs no angle or height — just the three sides.
A way to find a triangle's area from its three side lengths alone: A = √(s(s−a)(s−b)(s−c)), where s is the semi-perimeter.
They violate the triangle inequality — one side is as long as or longer than the other two combined, so the triangle cannot close.
Any side can be the base. Just make sure the height you use is measured perpendicular to that side.
Yes — use the three-sides method, which relies only on the side lengths.