atan() (Arc Tangent, in Radians) The atan() method is used to return the arctangent of its given parameter, number (see syntax). The result returned is a numeric value between the range of -PI/2 and PI/2, in radians. As with all mathematical methods, it is used with a Math object. syntax: Math.atan(number) EXAMPLE document.write("The arctangent of 62 is : " + Math.atan(62) + ".") The example shows a document.write statement being used to display some descriptive text along with the arctangent of the number 62. The output should look like the following: The arctangent of 62 is : 1.5546686929512603.