Triangle Calculator
Right triangle: enter the two short sides (a and b). It finds the hypotenuse, area and perimeter.
What is a triangle calculator?
A triangle calculator solves a right triangle using Pythagoras’ theorem. Example: sides 3 and 4 give hypotenuse 5, area 6 and perimeter 12.
How to use it
Enter the two legs a and b, then tap Calculate. To find a missing leg instead, choose Leg b mode and enter side a and hypotenuse c.
Formula
Pythagoras’ theorem: c² = a² + b². For 3 and 4: c² = 9 + 16 = 25, so c = 5. Area = ½ × a × b = 6. Perimeter = 3 + 4 + 5 = 12.
Example
A right triangle with legs 3 and 4 is the classic 3-4-5 triangle. The hypotenuse is √(3² + 4²) = √25 = 5, the area is ½ × 3 × 4 = 6, and the perimeter is 3 + 4 + 5 = 12.
Frequently Asked Questions
What is the hypotenuse of a 3-4 triangle?
5.
What is the area of a 3-4-5 triangle?
6.
What is the perimeter of a 3-4-5 triangle?
12.
More calculators: Math Tools and All Tools.