Right Triangle Calculator

Calculate the hypotenuse, area, perimeter, and angles of a right triangle from two legs.

Length of the first leg.

Length of the second leg.

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Right Triangle Properties

A right triangle has one 90° angle. The side opposite the right angle is the hypotenuse — the longest side. The other two sides are called legs. The Pythagorean theorem (a² + b² = c²) relates the three sides and is one of the most fundamental relationships in mathematics.

Calculating Angles in a Right Triangle

Since one angle is always 90°, the other two must sum to 90° (complementary). Use trigonometry: angle A = arctan(a/b) and angle B = arctan(b/a). Alternatively, angle A = arcsin(a/c) or arccos(b/c). All methods give the same result.

Common Right Triangle Ratios

Special right triangles have memorized ratios. The 3-4-5 triangle (and multiples like 6-8-10, 5-12-13) are Pythagorean triples. The 45-45-90 triangle has sides in ratio 1:1:√2. The 30-60-90 triangle has sides in ratio 1:√3:2. These shortcuts speed up calculations.

Applications of Right Triangles

Right triangles are used in construction (roof pitch), navigation (bearing calculations), surveying (measuring heights), physics (force components), and computer graphics (distance calculations). Trigonometric functions (sine, cosine, tangent) are all defined using right triangles.

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