Triangle Perimeter Calculator
P = a + b + c. Sum of all three sides.
Result
General calculation reads
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How to use this calculator
- Enter three side lengths.
- Calc verifies triangle inequality.
- Reads perimeter + area + type.
About this calculator
Triangle perimeter is just the sum of three sides. The triangle inequality requires each side < sum of the other two — otherwise it's not a real triangle. Heron's formula gives area from sides only: Area = √(s(s−a)(s−b)(s−c)) where s = P/2 is the semi-perimeter. Equilateral (all equal), isosceles (two equal), scalene (all different) classify by side equality.
Frequently asked
Triangle inequality?+
How does Heron's work?+
Equilateral special?+
Right triangle?+
Why semi-perimeter "s"?+
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