Right triangles
Choose “Right triangle” and leave the unknown side blank: Pythagoras (a² + b² = c²) finds it, with the two acute angles.
Three lengths can form a triangle only if each is shorter than the other two combined.
Frequently asked questions
What is Heron’s formula?
Area = √(s(s − a)(s − b)(s − c)), where s is half the perimeter.
How is the triangle type decided?
By its sides (equilateral, isosceles, scalene) and largest angle (acute, right, obtuse).
Is it free?
Yes.