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.