Right Triangle Calculator
Right triangle calculator
Compute hypotenuse, area, and perimeter from two legs.
InputsForm2 fieldsLive
Hypotenuse (c)
5
Uses c = √(a² + b²) for the side opposite the 90° angle.
Live update
Auto
math
Area
6
Perimeter
12
Leg a
3
Leg b
4
Advanced options
- Area uses square units when both legs share the same length unit.
- Perimeter stays in the same length unit as leg a, leg b, and c.
- This calculator assumes leg a and leg b meet at a 90° angle.
Formula
c = √(a² + b²)
For a right triangle, area = (a × b) / 2 and perimeter = a + b + c.
Formula
c = √(a² + b²) A = (a × b) / 2 P = a + b + c Symbol legend
| Symbol | Meaning | Unit | Copy |
|---|---|---|---|
a, b | Leg lengths of right triangle | length | |
c | Hypotenuse | length | |
A | Area | square units | |
P | Perimeter | length |
- Use Pythagorean theorem to compute hypotenuse c.
- Compute area with one-half times the product of the two perpendicular legs.
- Add all three side lengths to get perimeter in the same unit as the legs.
Example
Worked example: a = 3, b = 4
- 1 c = √(3² + 4²) = 5
- 2 A = (3 × 4) / 2 = 6
- 3 P = 3 + 4 + 5 = 12
Hypotenuse is 5, area is 6, and perimeter is 12.
How
- Enter leg a and leg b as the two perpendicular sides.
- Keep both legs in the same unit before reading area and perimeter.
- Read hypotenuse, area, and perimeter results.
Avoid
- Applying formulas to non-right triangles.
- Using inconsistent units between a and b.
- Confusing perimeter (linear units) with area (square units).
FAQ
Does this calculator require a right triangle?
Yes. Inputs are interpreted as the two perpendicular legs of a right triangle.
Can I provide hypotenuse as input?
This version is configured for two-leg input only.
Why are there three outputs?
It returns hypotenuse, area, and perimeter together for convenience.
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