When to use this calculator
For a right triangle, cosine relates the adjacent side to the hypotenuse. Check that your angle is in degrees.
Explore the trigonometry calculators for other questions in this topic. For a related calculation, use the Cotangent Calculator: Find the cotangent of an angle entered in degrees.
PUTTING IT INTO PRACTICE
Cosine: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Angle (degrees) | 60 |
| Result | 0.5 |
- Check the input labels and enter the example values above.
- Apply the relationship: cos(angle) = cos(degrees × π/180).
- The result is 0.5 , rounded for display.
How to interpret your result
Very large angles can lose precision in floating-point calculations.
These tools take degrees unless stated otherwise. A right-triangle ratio and the law of cosines solve different input patterns. For the sine rule, identify which side is opposite each supplied angle.
Frequently asked questions
Are the angle inputs in degrees or radians?
The trigonometry tools here label angles in degrees and convert internally. Use the degree-to-radian converter when another formula requires radians.
When is the cosine calculator useful?
For a right triangle, cosine relates the adjacent side to the hypotenuse. Check that your angle is in degrees.
How do I use the cosine calculator?
Enter angle (degrees). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
cos(angle) = cos(degrees × π/180).
What should I check before using the result?
Very large angles can lose precision in floating-point calculations.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see OpenStax: basic functions and identities ↗. This is a topic reference, not an external review or endorsement of this tool.
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