asin() (Arc Sine, in Radians) The asin() method is used to return the arcsine 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.asin(number) EXAMPLE document.write("The arcsine of 0.6973907898697076 is : " + Math.asin(0.6973907898697076) + ".") The example shows a document.write statement being used to display some descriptive text along with the arcsine of the number 0.6973907898697076 (which is the arctangent of the quotient of 62 and 74). The output should look like the following: The arcsine of 0.6973907898697076 is : 0.7717503825477446.