Right Triangle Calculator

Enter any two values of a right triangle to get every side and angle, plus area, perimeter and the altitude to the hypotenuse.

What Do You Want to Find?
Fractions and decimals both work.
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Hypotenuse
Sides
Angles
Area
Perimeter
Height to hypotenuse
sin, cos, tan of A
Work

Saved Calculations

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How to Solve a Right Triangle

Label the legs a and b and the hypotenuse c, with angle A opposite side a. Two values (at least one a side) fix the whole triangle.

a² + b² = c²   sin A = a/c   cos A = b/c   tan A = a/b   A + B = 90°
Area = a × b ÷ 2   Height to hypotenuse = a × b ÷ c

Worked Example

Tips

SOH-CAH-TOA: Sine = Opposite/Hypotenuse, Cosine = Adjacent/Hypotenuse, Tangent = Opposite/Adjacent. For a roof, stair or ramp, the rise and run are the legs and the rafter or stringer is the hypotenuse.