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Right Triangle Calculator
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Fill in exactly two values (sides a, b, c and/or angle A) - the right angle is always at C.
°
The right angle is always angle C (90°). Fill in exactly two of the four fields above.
| Leg a | 3 |
| Leg b | 4 |
| Hypotenuse c | 5 |
| Angle A | 36.87° |
| Angle B | 53.13° |
| Angle C | 90° |
| Perimeter | 12 |
| Area | 6 |
Solving a Right Triangle
In a right triangle, the right angle is always 90°, so the other two angles always add up to 90°. That relationship, combined with the Pythagorean theorem and the basic trig ratios (sine, cosine, tangent), means any two known values - two sides, or one side plus one acute angle - are enough to solve for everything else.
a² + b² = c²
sin(A) = a/c cos(A) = b/c tan(A) = a/b
Area and Perimeter
Once all three sides are known, the perimeter is just their sum, and since the two legs are perpendicular to each other, the area is simply half the product of the two legs (½ × a × b).