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;
// convert to radians
a = Math.toRadians(a);
b = Math.toRadians(b);
// 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.