Cosine Calculator
This cosine calculator returns the cosine for any angle you enter, in degrees or radians. Type the angle, choose the unit, and read the value, with the angle also shown in the other unit for reference. Cosine is one of the six trigonometric functions and describes a fixed ratio in a right triangle, or a coordinate on the unit circle, for a given angle. The calculator converts your angle to radians internally, since that is what the underlying maths uses, and rounds the answer for display. Use it for geometry and trigonometry study, physics and engineering work, surveying, navigation, or any time you need a quick, accurate trig value without a scientific calculator to hand. The definition, a worked example and the assumptions are set out below.
The formula
Cosine is the ratio of the side adjacent to the angle to the hypotenuse in a right triangle, and the x coordinate on the unit circle. The calculator computes cos of the angle in radians.
Worked example
Cosine of 60 degrees is 0.5. Enter 60 with degrees selected to confirm, then try 0 degrees to get 1.
Frequently asked questions
How do I find the cosine of an angle?
Enter the angle and pick degrees or radians. The calculator converts to radians and evaluates the cosine.
Degrees or radians?
Either. Choose the unit in the dropdown. The angle is shown in both units beside the result so you can check.
Why is the result the same every 360 degrees?
The trig functions are periodic. Sine and cosine repeat every 360 degrees (2 pi radians), so equivalent angles give the same value.
Who this calculator is for
This calculator is for students, engineers, surveyors and anyone who needs the cosine of an angle.
What this calculator assumes
- You enter a single angle in the chosen unit.
- The angle is converted to radians for the calculation.
- Results are rounded for display.
Formula and sources
Related calculators
- Trig Calculator: all six trig functions at once.
- Degrees to Radians Calculator: convert angle units.
- Right Angle Triangle Calculator: solve a right triangle.
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