CalculynQuick answer
A 3-4-5 triangle has area 6, perimeter 12, and angles 36.9°, 53.1° and 90°.
How it works
Heron's formula finds the area from the three sides, and the law of cosines finds each angle. Any valid triangle works — right, acute or obtuse.
Formula
s = (a+b+c)÷2 · Area = √(s(s−a)(s−b)(s−c)) · cos A = (b²+c²−a²)÷2bc
Assumptions & limitations
- Results are rounded for display.
Frequently asked questions
What if my sides can't form a triangle?
The two shorter sides must add up to more than the longest side — otherwise no triangle exists.