This online calculator finds the reference angle and the quadrant to a trigonometric angle in standard position. The reference angle is defined as the acute angle between the terminal side of the given angle and the x axis. The given angle may be in degrees or radians.
How to use the calculator
1  Enter the angle:
 in Degrees top input. (example 745)
 in Radians second input. (example 12/5 π)
then press the button "enter" on the same row.
If you enter a quadrantal angles such as 90, 180, 0..., the message "This is a quadrantal angle" will be displayed.
