Triangle Calculator
Free triangle calculator — updated for 2025. Accurate, instant, no sign-up needed.
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Triangle Calculator
Area, perimeter, angles & side lengths
Area
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Perimeter
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Type
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Angle A
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Angle B
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Angle C
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Triangle Formulas
Area (Heron's) = √(s(s-a)(s-b)(s-c)), s = (a+b+c)/2
Law of Cosines: c² = a² + b² − 2ab·cos(C)