Desmos Convert Radians to Degrees: How-To
- Radians
- 1.5707963268 rad
- You entered
Desmos does not have a one-click convert button, but you can convert radians to degrees in the graphing calculator and the scientific calculator by multiplying by 180/π or by using the built-in degrees() function. For example, to convert π/2 radians, type π/2 * 180/π or degrees(π/2) and Desmos will return 90. This article explains both methods, how to use them in expressions and tables, and answers common questions about angle modes in Desmos.
Formula
The conversion from radians to degrees uses the identity that a full circle is 2π radians or 360°. Therefore:
Degrees = Radians × (180 / π)
Where:
- Radians – the angle you want to convert (unit: rad)
- Degrees – the result in degrees (unit: °)
- π – the mathematical constant approximately equal to 3.14159265
This works because 180° equals π radians, so multiplying by the fraction (180/π) cancels the radian unit and leaves degrees.
Worked Example
Using the default value of 1.5707963267948966 radians (which is exactly π/2):
- Start with the formula: Degrees = Radians × (180 / π)
- Plug in the value: Degrees = 1.5707963267948966 × (180 / 3.141592653589793)
- Calculate the fraction: 180 / 3.141592653589793 ≈ 57.29577951308232
- Multiply: 1.5707963267948966 × 57.29577951308232 = 90.00000000000001
Rounded to two decimals, the result is 90.00°. This matches what Desmos shows when you enter π/2 * 180/π or degrees(π/2).
Why Convert Radians to Degrees in Desmos?
Most people learn angles in degrees first, so converting makes results more intuitive. For example, if you are graphing a sine wave and want the x-axis to show 0°, 90°, 180°, 270°, 360° instead of 0, 1.57, 3.14, 4.71, 6.28, you need to convert. Also, some problems in physics or engineering give answers in radians, but you need degrees for a final report. Desmos does not have a global setting to switch the graphing calculator to degree mode – it always interprets trig functions as radians. So the conversion must be done manually in your expression.
How to Use the Conversion in Desmos
There are two main ways to convert in Desmos:
- Multiplication method: Type your radian value and multiply by
180/π. For instance,3 * 180/πgives 171.887°. This works in any Desmos calculator. - Degrees function: Desmos has a built-in function
degrees()that converts radians to degrees. For example,degrees(1)returns 57.2958°. This is cleaner and easier to read.
You can also use the conversion inside larger expressions. For example, to graph a sine wave with degrees on the x-axis, you could write y = sin(x * π/180) – this converts degrees to radians internally. Or to plot a point at 45°, you could use (45, sin(45 * π/180)).
Common Mistakes and How to Avoid Them
The most common mistake is forgetting that Desmos uses radians by default. If you type sin(90) expecting 1, you get 0.894 because 90 radians is not 90 degrees. Another mistake is mixing up the conversion factor: to go from radians to degrees you multiply by 180/π, not π/180. The latter converts degrees to radians. A third issue is using the degrees() function on a value that is already in degrees – it will give a nonsense number. Always double-check your input: if you are converting 2 radians, use degrees(2) or 2 * 180/π.
Using the Conversion in Tables and Sliders
Desmos allows you to create tables and sliders that can use the conversion. For a table, you can define a column with radian values and a second column with the conversion formula. For example, in a table, set x_1 to 0, 0.5, 1, 1.5, 2 and set y_1 to x_1 * 180/π. Desmos will fill in the degrees. For sliders, you can set a slider for radians and then display the degrees in a folder or a label. This is useful when you want to see both units simultaneously.
Limitations of the Conversion
The conversion is straightforward, but there are a few limitations. First, the degrees() function only works with numeric values, not with lists or points directly – you need to apply it element-wise. Second, when graphing, the x-axis labels remain in the units you type; Desmos does not automatically label the axis as degrees or radians. You have to add a label manually. Third, if you use the conversion on a value that is already in degrees, you will get a wrong result – the function does not check units. Finally, for very large radian values, the result may be large but still correct; there is no wrap-around to 0–360° unless you add a modulo operation.
Frequently Asked Questions
Does Desmos have a degree mode?
No, the Desmos graphing calculator does not have a global degree mode. It always interprets trigonometric functions (sin, cos, tan) as taking radians. However, you can manually convert degrees to radians by multiplying by π/180, or use the radians() function. For example, to compute sin(30°) you would type sin(30 * π/180) or sin(radians(30)).
What is the difference between degrees() and radians() in Desmos?
degrees(x) converts a value from radians to degrees, while radians(x) converts from degrees to radians. For instance, degrees(π) returns 180, and radians(180) returns π. They are inverse functions of each other.
Can I use the conversion in a Desmos table?
Yes, you can use the conversion in a table. For example, in a table, set the first column to radian values and the second column to radian_value * 180/π. Desmos will compute the degrees for each row. Alternatively, you can use degrees(radian_value).
Why does sin(90) not equal 1 in Desmos?
Because Desmos interprets 90 as 90 radians, not 90 degrees. 90 radians is about 5156.62°, and the sine of that is not 1. To get sin(90°), you need to convert: sin(90 * π/180) or sin(radians(90)).
Is there a keyboard shortcut for π in Desmos?
Yes, you can type pi (without spaces) and Desmos will convert it to the π symbol. Alternatively, you can use the Greek keyboard or copy and paste the π character.
Can I convert a list of radians to degrees at once?
Yes, you can apply the conversion to a list. For example, if you have a list L = [0, 1.57, 3.14], you can type L * 180/π and Desmos will return a list of degrees. The degrees() function also works on lists.
Related
Formula used
in rad | Radians | rad | 1.5707963267948966 | 0 out deg | Degrees | ° | rad * 180 / pi | 2
Each line is one input (in, sel, list) or one result (out: label, unit, formula, decimals). How the calculators work
Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.