JavaScript Math.acos() Method

Programmers can use the Math.acos() method to get the inverse cosine of the number value.

When we take a cosine of an angle, it gives the number values as an output, and an arc-cosine takes a number value and gives the angle in radians in the output.

Syntax of JavaScript Math.acos() Method

let val = 0.5;
Math.acos(val);

Parameters

val - The val is a number in the range [-1,1].

Return

The Math.acos() returns the angle related to val in radians, means between [0,PI].

Example 1: Use the Math.acos() Method With Values Between -1 to 1

In the example below, we have used the Math.acos() method to get the inverse cosine value of different numbers in the range [-1,1]. In the output, users can observe that it returns a single value, an angle in radians.

let val1 = 0.5;
let val2 = -0.5;
console.log(Math.acos(val1));
console.log(Math.acos(val2));
console.log(Math.acos(-0.0001));
console.log(Math.acos(0.999));

Output:

1.0471975511965979
2.0943951023931957
1.5708963267950633
0.044725087168733454

Example 2: Use the Math.acos() Method With Values Not Between -1 to 1

When we take the val parameter outside the [-1,-1], it always returns the NaN values. The reason to return the NaN value is the domain of the arc-cosine is [-1,-1], and when users try to find the output for the value that is out of the domain, it gives NaN as an output.

let val1 = 1.5;
let val2 = -1.5;
console.log(Math.acos(val1));
console.log(Math.acos(val2));

Output:

NaN
NaN

Example 3: Use the Math.acos() Method With Non-Numeric Values

In the example below, we are trying to find the output of the Math.acos() method for the non-numeric values such as Infinity and string values. In such a case, it returns the NaN values as an output.

let val1 = Infinity;
let val2 = "Delft";
console.log(Math.acos(val1));
console.log(Math.acos(val2));

Output:

NaN
NaN

This article has seen various examples and use cases of the Math.acos() method.