Cosine Calculator
Compute the cosine of an angle, in degrees or radians.
Calculator
Use the Cosine Calculator
Result
—
Formula
cos(θ)
Step-by-step
- 1
Enter the angle
Any numeric value.
- 2
Pick the unit
Degrees or radians.
Worked example
Example input: angle: 60, mode: deg
Result: 0.5
Related tools
- Sine Calculator
sin(θ).
- Tangent Calculator
tan(θ).
Frequently asked questions
What is cos of 60 degrees?
0.5, exactly. In a 30-60-90 triangle the side next to the 60° angle is half the hypotenuse, and cosine is adjacent over hypotenuse. Enter 60 with the degree unit selected above and you get the same 0.5 shown in the example. Relying on the same logic, cos(45 deg) gives about 0.7071 while cos(30 deg) is √3 over 2, so neighboring angles fall off smoothly.
Where is cosine negative?
Between 90° and 270° — the quadrants where the unit-circle x-coordinate is negative. That is why cos(120°) ≈ -0.5 and cos(200°) ≈ -0.94, while angles inside 0-90° or 270-360° give positive values.
How do cosine and sine connect?
They are the same wave shifted a quarter turn: sin(θ) = cos(90° − θ). That pairing is why our sine and cosine calculators agree on swapped angles — cos(30°) equals sin(60°), and cos(60°) equals sin(30°).