Cosine Calculator

Calculate cosine of any angle. Free online cos calculator for degrees and radians.

The Cosine Calculator finds the cosine value of any angle in degrees or radians. Cosine represents the ratio of the adjacent side to the hypotenuse in a right triangle and is essential for calculating projections, components, and phases. Used extensively in physics, engineering, computer graphics, and signal processing.

Common use cases

  • Vector component calculations
  • Phase shift analysis
  • 3D rotation matrices
  • Signal processing
  • Structural engineering

How to use

  1. Enter the angle value
  2. Select degrees or radians
  3. Click calculate for cos(θ)
  4. View the precise result
  5. Compare with sine and tangent

FAQ

What is cosine?

In a right triangle, cos(θ) = adjacent side ÷ hypotenuse. It ranges from -1 to 1.

What are key cosine values?

cos(0°)=1, cos(30°)≈0.866, cos(45°)≈0.707, cos(60°)=0.5, cos(90°)=0.

How does cosine relate to sine?

cos(θ) = sin(90° - θ). They're complementary functions, hence 'co-sine'.

When is cosine negative?

Cosine is negative for angles between 90° and 270° (second and third quadrants).