Right Triangle Calculator

Calculate sides, angles, area, and perimeter of right triangles.

Result

Fill in the fields above, then press Calculate.

A right triangle calculator solves for missing sides, angles, area, and perimeter of a right triangle given two known measurements.

Choose between entering two sides or one side plus one angle. The calculator will solve for all unknown sides and angles of the right triangle, plus compute area, perimeter, and radii.

Examples

3-4-5 triangle

a=3, b=4: c=5, A≈36.87°, B≈53.13°, Area=6

Angle and side

Angle 30°, hypotenuse 10: a=5, b=8.66

45-45-90

a=1, b=1: c=√2≈1.414, angles are both 45°

Frequently Asked Questions

What are SOH-CAH-TOA?
Memory aids for trig ratios: Sin = Opposite/Hypotenuse, Cos = Adjacent/Hypotenuse, Tan = Opposite/Adjacent.
What is the inradius?
The inradius is the radius of the largest circle that fits inside the triangle. For a right triangle: r = (a + b - c) / 2.
What is the circumradius?
The circumradius is the radius of the circle that passes through all three vertices. For a right triangle: R = c / 2 (half the hypotenuse).
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Quick Tips

  • •Double-check your inputs — small errors lead to incorrect results.
  • •Remember to convert degrees to radians if your formula requires it.
  • •Use SOH-CAH-TOA to verify trigonometric results independently.