Triangle Area Calculator
Area from base and height, or from three sides using Heron's formula.
The two formulas
Base and height: area = base × height / 2. The height must be perpendicular to the base, not a slanted side.
Heron's formula, when you know all three sides: with s = (a+b+c)/2,
area = √(s(s-a)(s-b)(s-c))
Sides 5, 6, 7 give s = 9 and area = √(9·4·3·2) = √216, about 14.7.
When Heron says no
If one side is longer than the other two combined, no triangle exists and the formula's square root goes negative. The calculator checks the triangle inequality first and tells you.