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Sine (sin) Calculator

Sine (sin) Calculator

Calculated sin() of the number

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sin() function

The sine of an angle is the ratio of the length of the side opposite that angle to the length of the hypotenuse, in a right triangle. The easiest way to picture it is on the unit circle: for an angle θ measured from the positive x-axis, sin(θ) is the y-coordinate of the point where the angle's ray crosses the circle.

This is a free online sin calculator — enter a value above and the sin() result updates automatically.

Important Abbreviations to Remember

  • SOH: Opposite / Hypotenuse (Sine)
  • CAH: Adjacent / Hypotenuse (Cosine)
  • TOA: Opposite / Adjacent (Tangent)

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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.

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