Java Math acos() method with Examples

The java.lang.Math.acos() returns the arc cosine of an angle in between 0.0 and pi. Arc cosine is also called as inverse of a cosine.If the argument is NaN or its absolute value is greater than 1, then the result is NaN.

Syntax :

public static double acos(double a)
Parameter :
a : the value whose arc cosine is to be returned.
Return :
This method returns the arc cosine of the argument.

Example :To show working of java.lang.Math.acos() method.

// Java program to demonstrate working
// of java.lang.Math.acos() method
import java.lang.Math;

class Gfg {

    // driver code
    public static void main(String args[])
    {
        double a = Math.PI;

        // Output is NaN, because Math.PI gives 3.141 value
        // greater than 1
        System.out.println(Math.acos(a));

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

        System.out.println(Math.acos(b));

        double c = 1.0;
        double d = 0.0;
        double e = -1.0;
        double f = 1.5;

        System.out.println(Math.acos(c));
        System.out.println(Math.acos(d));
        System.out.println(Math.acos(e));

       // value of f does not lie in between -1 and 1
       // so output is NaN
        System.out.println(Math.acos(f));
    }
}

Output:

NaN
1.5159376794536454
0.0
1.5707963267948966
3.141592653589793
NaN