Java Math cos()

The syntax of the `cos()` method is:

``Math.cos(double angle)``

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

cos() Parameters

The `cos()` method takes a single parameter.

• angle - angle whose trigonometric cosine is to be returned

Note: The value of the angle is in radians.

cos() Return Value

• returns the trigonometric cosine of the specified angle
• returns NaN if the specified angle is NaN or infinity

Example 1: Java Math cos()

``````import java.lang.Math;

class Main {
public static void main(String[] args) {

// create variable in Degree
double a = 30;
double b = 45;

// print the cosine value
System.out.println(Math.cos(a));  // 0.8660254037844387
System.out.println(Math.cos(b));  // 0.7071067811865476
}
}``````

In the above example, we have imported the `java.lang.Math` package. This is important if we want to use methods of the `Math` class. Notice the expression,

``Math.cos(a)``

Here, we have directly used the class name to call the method. It is because `cos()` is a static method.

Note: We have used the Java Math.toRadians() method to convert all the values into radians. It is because as per the official documentation, the `cos()` method takes the angle as radians.

Example 2: Math cos() Returns NaN

``````import java.lang.Math;

class Main {
public static void main(String[] args) {

// create variable
// square root of negative number
// results in not a number (NaN)
double a = Math.sqrt(-5);

// Using Double to implement infinity
double infinity = Double.POSITIVE_INFINITY;

// print the cosine  value
System.out.println(Math.cos(a));  // NaN
System.out.println(Math.cos(infinity));  // NaN
}
}``````

Here, we have created a variable named a.

• Math.cos(a) - returns NaN because square root of a negative number (-5) is not a number

The `Double.POSITIVE_INFINITY` is a field of `Double` class. It is used to implement infinity in Java.

Note: We have used the Java Math.sqrt() method to compute the square root of a number.