△MATH
Triangle Calculator
Calculate the perimeter and area of a triangle from its three side lengths.
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Formula
Perimeter = a + b + c. Heron's formula: area = √(s(s − a)(s − b)(s − c)), where s = perimeter ÷ 2.
Perimeter = a + b + c. Heron's formula: area = √(s(s − a)(s − b)(s − c)), where s = perimeter ÷ 2.
How it works
1
Enter all three side lengths.
2
The calculator checks the triangle inequality.
3
Review perimeter and area.
Important notes
The side lengths must satisfy the triangle inequality.