math
Right Triangle Calculator
Solve a right triangle from its two legs: hypotenuse, angles, area, and perimeter.
Hypotenuse (c)
5
Angle A (opposite a)
36.87°
Angle B (opposite b)
53.13°
Area
6
Perimeter
12
How it works
- 1Enter the lengths of the two legs (a and b).
- 2The hypotenuse is √(a² + b²); the angles come from the arctangent of the legs.
- 3Read the hypotenuse, both acute angles, area, and perimeter.
Use cases
- Find a roof, ramp, or staircase diagonal.
- Get the angles of a right triangle from its sides.
- Check right-triangle trigonometry homework.
Frequently asked questions
How do you find the hypotenuse?
Use the Pythagorean theorem: hypotenuse = √(a² + b²). For legs 3 and 4 the hypotenuse is 5.
How are the angles found?
Angle A (opposite leg a) is arctan(a ÷ b), and angle B is 90° − A, since the angles of a right triangle add to 180°.
What if I enter a zero leg?
A right triangle needs two positive legs, so zero or negative inputs show "—".
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