The arcsine is the inverse of the sine function.
The syntax of the asin()
method is:
Math.asin(double num)
Here, asin()
is a static method. Hence, we are accessing the method using the class name, Math
.
asin() Parameters
The asin()
method takes a single parameter.
- num - number whose arc sine is to be returned
Note: The absolute value of num should be always less than 1.
asin() Return Value
- returns the arcsine of the specified number
- returns 0 if the specified value is zero
- returns
NaN
if the specified number isNaN
or greater than 1
Note: The returned value is an angle between -pi/2 to pi/2.
Example 1: Java Math asin()
import java.lang.Math;
class Main {
public static void main(String[] args) {
// create variable
double a = 0.99;
double b = 0.71;
double c = 0.0;
// print the arcsine value
System.out.println(Math.asin(a)); // 1.4292568534704693
System.out.println(Math.asin(b)); // 0.7812981174487247
System.out.println(Math.asin(c)); // 0.0
}
}
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.asin(a)
Here, we have directly used the class name to call the method. It is because asin()
is a static method.
Example 2: Math asin() Returns NaN
import java.lang.Math;
class Main {
public static void main(String[] args) {
// create variable
double a = 2;
// square root of negative number
// results in not a number (NaN)
double b = Math.sqrt(-5);
// print the arc sine value
System.out.println(Math.asin(a)); // NaN
System.out.println(Math.asin(b); // NaN
}
}
Here, we have created two variables named a and b.
- Math.asin(a) - returns NaN because value of a is greater than 1
- Math.asin(b) - returns NaN because square root of a negative number (-5) is not a number
Note: We have used the Java Math.sqrt() method to compute the square root of a number.