JavaScript Math asin()

The asin() method calculates the arcsine (inverse of sine) of the specified angle and returns it.


let value = Math.asin(1);

// Output: 1.5707963267948966

asin() Syntax

The syntax of the Math.asin() method is:


Here, asin() is a static method. Hence, we are accessing the method using the class name, Math.

asin() Parameter

The asin() method takes a single parameter:

  • angle - in radians whose arcsine is to be calculated

Note: The value of angle should be between -1 and 1.

asin() Return Value

The asin() method returns:

  • arcsine value of the angle
  • NaN (Not a Number) if the argument is either non-numeric or greater than 1 or less than -1

Example 1: Math.asin() with argument between -1 and 1

// arcsine of negative number let number1 = Math.asin(-1);
// arcsine of positive number let number2 = Math.asin(0.5);
console.log(number2); // Output: // -1.5707963267948966 // 0.5235987755982989

In the above example, the Math.asin() method computes the arcsine of

  • -1 (negative number) - results in -1.5707963267948966
  • 0.5 (positive number) - results in 0.5235987755982989

Example 2 : Math.asin() for other Argument not in the range -1 and 1

// argument less than -1 let number1 = Math.asin(-100);
console.log(number1); // Output: NaN
// argument greater than 1 let number2= Math.asin(32)
; console.log(number2); // Output: NaN

Here, we get NaN as output because both the arguments, -100 and 32, are not in the range -1 and 1.

Example 3: Math.asin() with Non-Numeric Argument

let string = "Harry";
// asin() with a string argument let value = Math.asin(string);
console.log(value); // Output: // NaN

In the above example, we have tried to calculate the arcsine of the string "Harry". That's why we get NaN as the output.

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