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Triangle Calculator

Area, perimeter and type from three sides

Enter the three side lengths (Heron’s formula).

Frequently Asked Questions

How is the area of a triangle found from three sides?
By Heron’s formula: with s = (a+b+c)/2 (the semi-perimeter), area = √(s(s−a)(s−b)(s−c)). The three sides must satisfy the triangle inequality.


Find the area (Heron’s formula), perimeter and type of a triangle from its three sides.