Cosine measures the horizontal ratio of an angle on the unit circle or the adjacent-to-hypotenuse ratio in a right triangle. It repeats regularly and stays from -1 to 1.
⚠Make sure the selected unit matches your input. For example, 60 degrees and 60 radians are very different angles.
How Cosine Works
On the unit circle, cosine is the x-coordinate at angle θ. In right triangles, it relates the angle to the adjacent side and hypotenuse.
Right Triangle
cos(θ) = adjacent / hypotenuse.
Unit Circle
Cosine is the x-coordinate.
Range
The value is always from -1 to 1.
Period
Cosine repeats every 360° or 2π.
💡 Example: For 60°, cos(60°)=0.5.
Applications of Cosine
Right TrianglesVectorsRotationsEngineering
Frequently Asked Questions
What is a cosine calculator?▼
It calculates cos(x) for an angle entered in degrees or radians.
What is the cosine formula?▼
In a right triangle, cosine is adjacent side divided by hypotenuse: cos(θ)=adjacent/hypotenuse.
How do I use this calculator?▼
Enter an angle, choose degrees or radians, and click Calculate.
What values can cosine have?▼
Cosine values range from -1 to 1 for all real angles.
Where is cosine used?▼
Cosine is used in triangles, vectors, waves, rotations, physics, and engineering.
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