Open In App

# StrictMath acos() Method in Java

The java.lang.StrictMath.acos() is an inbuilt method which returns cosine of a given argument and an angle. The angle which is returned within the range between 0.0 and pi. Note: If the absolute value of the argument is greater than 1 or the argument is itself a NaN then the result is also NaN. Syntax:

`public static double acos(double num)`

Parameters: The method accepts one parameter num which is of double type and refers the arc whose cosine is to be returned. Return Value: The method returns the arc cosine of the argument. Examples :

```Input: num = 0.45
Output: 1.1040309877476002

Input: num = 8.9
Output: NAN```

Below programs illustrate the java.lang.StrictMath.acos() method: Program 1: For positive number

## java

 `// Java program to illustrate the``// java.lang.StrictMath.acos()``import` `java.lang.*;` `public` `class` `Geeks {` `    ``public` `static` `void` `main(String[] args)``    ``{` `        ``double` `num1 = ``0.65``, num2 = ``6.30``;` `        ``// It returns the arc cosine of a value``        ``double` `acosValue = StrictMath.acos(num1);``        ``System.out.println("The arc cosine value of "+``                             ``num1 + " = " + acosValue);` `        ``acosValue = StrictMath.acos(num2);``        ``System.out.println("arc cosine value of "+``                             ``num2 + " = " + acosValue);``    ``}``}`

Output:

```The arc cosine value of 0.65 = 0.863211890069541
arc cosine value of 6.3 = NaN```

Program 2: For negative number.

## java

 `// Java program to illustrate the``// java.lang.StrictMath.acos()``import` `java.lang.*;` `public` `class` `Geeks {` `    ``public` `static` `void` `main(String[] args)``    ``{` `        ``double` `num1 = -``0.65``, num2 = -``6.30``;` `        ``// It returns the arc cosine of a value``        ``double` `acosValue = StrictMath.acos(num1);``        ``System.out.println("The arc cosine value of "+``                             ``num1 + " = " + acosValue);` `        ``acosValue = StrictMath.acos(num2);``        ``System.out.println("arc cosine value of "+``                             ``num2 + " = " + acosValue);``    ``}``}`

Output:

```The arc cosine value of -0.65 = 2.278380763520252
arc cosine value of -6.3 = NaN```