Right Triangle Calculator
Enter any two values of a right triangle and get the rest. Use two legs, a leg with the hypotenuse, or one side with angle A to find every side and angle.
How to solve a right triangle
- Enter exactly two known values for the triangle.
- Use two legs, a leg and the hypotenuse, or a side with angle A.
- Read the remaining sides, both acute angles, the area and the perimeter.
Examples
Two legs (3-4-5 triangle)
legA = 3, legB = 4
hypotenuse 5, angle A 36.87, angle B 53.13, area 6
Leg and angle
legA = 5, angle A = 30 degrees
hypotenuse 10, legB 8.6603, area 21.6506
Frequently asked questions
What is a right triangle?
A right triangle has one 90 degree angle. The two shorter sides are the legs and the longest side, opposite the right angle, is the hypotenuse.
How many values do I need to solve a right triangle?
You need exactly two, and at least one must be a side length. Two legs, a leg and the hypotenuse, or one side and angle A all work.
Which angle is angle A?
Angle A is the acute angle opposite leg a. Angle B is opposite leg b, and the two acute angles always add up to 90 degrees.
Why can a leg not equal the hypotenuse?
The hypotenuse is always the longest side. If a leg is equal to or longer than the hypotenuse, no real right triangle exists, so the input is rejected.
Are angles in degrees or radians?
Angle A is entered in degrees, so 30 means 30 degrees. It is converted to radians internally before any sine, cosine or tangent is taken.
Related tools
Pythagorean Theorem Calculator
Find the missing side of a right triangle with a squared plus b squared equals c squared. Get the legs, hypotenuse, area and perimeter instantly.
Triangle Area Calculator
Find the area of a triangle from base and height, three sides (Heron's formula) or two sides and an angle (SAS). Free, accurate and instant.
Special Right Triangle Calculator
Find every side of a 45-45-90 or 30-60-90 triangle from one known side. Uses the fixed ratios to return all sides, the area and the perimeter instantly.
Trig Functions Calculator
Calculate sin, cos, tan, csc, sec and cot for any angle in degrees or radians. Undefined functions, like tan at 90 degrees, are clearly flagged.
Annulus Area Calculator
Calculate the area of an annulus, the ring between two concentric circles, from its outer and inner radius. Returns both circumferences and width too. Free.
Area Calculator
Find the area of a circle, square, rectangle, triangle, trapezoid, parallelogram, ellipse, sector or rhombus. Free and runs in your browser.