Cosine Calculator

Compute cos(x) for any angle.

Inputs

Result

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How to use this calculator

  • Enter angle and unit.
  • Read cosine plus matching sin/tan.

About this calculator

cos(x) is the x-coordinate of the unit-circle point at angle x. Range [−1, 1], period 2π. Key values: cos(0°) = 1, cos(60°) = ½, cos(90°) = 0, cos(180°) = −1.

Frequently asked

How does cos relate to sin?+
cos(x) = sin(90° − x). Pythagorean identity: sin² + cos² = 1.
cos(90°) is exactly 0?+
Mathematically yes. Floating point may show 6.12e-17 — effectively zero.
Why is cos(180°) = −1?+
At 180° you're at (−1, 0) on the unit circle, so the x-coordinate is −1.
What is cos used for?+
Anywhere periodic motion or projection appears: physics waves, signal processing, navigation, computer graphics rotation.
How is cos different from arccos?+
cos: angle → ratio. arccos: ratio → angle. They're inverses on the principal branch [0, π].

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Degrees to Radians Converter
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