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Right Triangle Solver

Right Triangle Solver

A right triangle has one 90° angle. Label the right angle C, with side c its opposite (the hypotenuse), and sides a and b opposite angles A and B. Enter any two of the four values below — two sides, or one side and one acute angle — and the rest, including angle B, are solved for automatically using the Pythagorean theorem and basic trigonometric ratios.

a squared plus b squared equals c squared, the Pythagorean theorem

Enter any two of the four values above (at least one must be a side) — the rest fill in automatically.

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What do the symbols mean?

a, bThe two legs, opposite angles A and B
cThe hypotenuse, opposite the right angle (C)
A, BThe two acute angles — always add up to 90°

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Understanding the Main Trigonometric Functions

The trigonometric functions — also called circular or goniometric functions — are functions of an angle that relate the angles of a right triangle to the lengths of its sides. They're central to the study of triangles and to modeling periodic phenomena (waves, oscillations, rotation), among many other applications in physics, engineering and geometry.

Every value below is computed from a triangle inscribed in the unit circle — sine and cosine are the vertical and horizontal legs of that triangle, and the other four functions (tangent, secant, cosecant, cotangent) are ratios built from them. Drag the point around the circle to see how each ratio changes with the angle. A handful of angles (0°, 90°, 180°, 270°, 360°) make one of those ratios divide by zero — those are undefined rather than a nonsensical number.

Other Trigonometric Calculators

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