ABC Triangle Calculator
Classify a triangle by its three side lengths as equilateral, isosceles, or scalene. Calculate area using Heron's formula. Free online triangle solver.
About This Calculator
The ABC Triangle Calculator takes three side lengths, validates them using the triangle inequality theorem, classifies the triangle type, and calculates the area using Heron's formula and the perimeter.
Triangle types: Equilateral (3 equal sides), Isosceles (2 equal sides), Scalene (no equal sides).
Frequently Asked Questions
How do you classify a triangle by its sides?
A triangle is equilateral if all three sides are equal, isosceles if exactly two sides are equal, and scalene if all sides are different. The calculator uses a tolerance of 0.01 for side comparisons.
What is the triangle inequality theorem?
The triangle inequality theorem states that the sum of any two sides must be greater than the third side: a + b > c, a + c > b, and b + c > a. If any inequality fails, the three sides cannot form a valid triangle.
How do you find the area of a triangle with three sides?
Use Heron's formula: Area = sqrt(s(s-a)(s-b)(s-c)), where s = (a+b+c)/2 is the semiperimeter. First verify the triangle inequality, then compute s, then apply the formula. This works for any valid triangle.