Triangle Calculator

Solve any triangle given 3 sides (SSS) — area, angles, perimeter.

Calculator Numbers & Math Updated Apr 19, 2026
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Sides
Triangle

Formulas

Heron area
√(s(s−a)(s−b)(s−c)), s = (a+b+c)/2
Law of cosines
cos A = (b² + c² − a²) / (2bc)

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