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JavaScript Math.acos()

 In JavaScript, Math.acos() is a method of the Math object that returns the arccosine (inverse cosine) of a number.

 The result is expressed in radians, which is a measure of angle.

Syntax


Math.acos(x)
  • x: A number between -1 and 1 (inclusive). The function calculates the arccosine of this number.

Returns

  • The method returns a number between 0 and π radians (0 to π, inclusive), which is the angle whose cosine is x.

Key Points

  • Domain: The input value (x) must be between -1 and 1, inclusive. Values outside this range result in NaN (Not-a-Number).
  • Range: The output is between 0 and π radians.

Examples

Here are 10 examples demonstrating how Math.acos() works:

  1. Basic Arccosine


    console.log(Math.acos(1)); // 0 (cos(0) = 1)

  2. Arccosine of 0


    console.log(Math.acos(0)); // 1.5707963267948966 (π/2 radians)

  3. Arccosine of -1


    console.log(Math.acos(-1)); // 3.141592653589793 (π radians)

  4. Arccosine of 0.5


    console.log(Math.acos(0.5)); // 1.0471975511965979 (π/3 radians)

  5. Arccosine of -0.5


    console.log(Math.acos(-0.5)); // 2.0943951023931957 (2π/3 radians)

  6. Arccosine of 0.25


    console.log(Math.acos(0.25)); // 1.318116071652818

  7. Arccosine of -0.25


    console.log(Math.acos(-0.25)); // 1.8234765819369757

  8. Arccosine of a number slightly less than -1


    console.log(Math.acos(-1.00001)); // NaN (Out of domain)

  9. Arccosine of a number slightly more than 1


    console.log(Math.acos(1.00001)); // NaN (Out of domain)

  10. Arccosine of 0.9


    console.log(Math.acos(0.9)); // 0.45102681179626236

Usage Notes

  • The result of Math.acos() is in radians. To convert the result to degrees, you can use the formula:


    function radiansToDegrees(radians) {
  return radians * (180 / Math.PI);
}

let radians = Math.acos(0.5);
console.log(radiansToDegrees(radians)); // 60 (degrees)

  • Ensure that the input to Math.acos() is within the valid range [-1, 1]. Values outside this range will return NaN.

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