Triangle area (Heron’s formula)
Calculate the area and semi-perimeter of any valid triangle from the lengths of its three sides.
Open calculatorPythagorean theorem
Leave one of the three fields empty. Entering both legs (a and b) solves for the hypotenuse c = √(a² + b²); entering one leg and a longer hypotenuse solves for the other leg. Area = (a × b) / 2.
Hypotenuse c
5
Leg a
3
Leg b
4
Triangle area
6
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3–4–5 is the classic integer Pythagorean triple (9 + 16 = 25).
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Educational estimate only. Not medical, tax, legal or financial advice.