JavaScript Math cos()

In this tutorial, you will learn about the JavaScript Math.cos() method with the help of examples.

The cos() method computes the trigonometric cosine of the specified angle and returns it.


// cosine of the angle 1
let value = Math.cos(1);

// Output: 0.5403023058681398

cos() Syntax

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


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

cos() Parameter

The cos() method takes a single parameter:

  • angle - in radians whose cosine value is to be calculated

cos() Return Value

The cos() method returns:

  • cosine value of the given angle (in radians)
  • NaN (Not a Number) for a non-numeric argument

Example 1: JavaScript Math.cos()

// cosine of 5 radians let value1 = Math.cos(5);
// negative radians are allowed let value2 = Math.cos(-2);
console.log(value2); // Output: // 0.28366218546322625 // -0.4161468365471424

In the above example,

  • Math.cos(5) - computes the cosine value of the angle 5
  • Math.cos(-2) - computes the cosine value of the angle -2

Example 2: Math.cos() with Math Constants

// math constants as arguments let value3 = Math.cos(Math.PI);
console.log(value3); // Output: -1

In the above example, we have used the cos() method to compute the cosine of the math constant PI.

Example 3: Math.cos() with Non-Numeric argument

let string = "Darth Vader";

// cos() with string as argument let value = Math.cos(string);
console.log(value); // Output: // NaN

In the above example, we have tried to calculate the cosine value of the string "Darth Vader" resulting in NaN as the output.

Example 4: Math.cos() with Infinity

// infinity as argument let value1 = Math.cos(Infinity);
// negative infinity as argument let value2 = Math.cos(-Infinity);
console.log(value2); // Output: // NaN // NaN

The cos() method doesn't treat infinity as a number so the method returns NaN with this argument.

Also, the cosine of an infinite angle is indefinite, which can't be defined with a number.

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