C# | Math.Asin() Method

Math.Asin() is an inbuilt Math class method which returns the angle whose sine value is given as a double value argument. If the argument is NaN, then the result will be NaN.

Syntax:

public static double Asin(double num)

Parameter:

num: It is the number that represents a sine and type of this parameter is System.Double. It must be greater than or equal to -1, but less than or equal to 1.

Return Type: Returns an angle Θ, measured in radians and its type is System.Double. Here the angle is always measured in radians, such that -π/2 ≤ Θ ≤ π/2.

Note: If the value of the num is greater than 1 or less than -1 or equals to NaN, then this method always returns NaN as result. To convert the radians(return value) to degrees multiply it by 180 / Math.PI. A positive return value always represents a counter clock-wise angle from the x-axis and a negative return value always represents a clockwise angle.

Examples:

Input  : Math.Asin(2)
Output : NaN

Input  : Math.Asin(0.3584)
Output : 0.366553473829125
     
Input  : Math.Asin(0.0)
Output : 0

Input  : Math.Asin(-0.0)
Output : 0

Input  : Math.Asin(Double.PositiveInfinity)
Output : NaN

Input  : Math.Asin(Double.NegativeInfinity)
Output : NaN

Program: To illustrate the Math.Asin() method

// C# program to demonstrate working
// of Math.Asin() method
using System;

class Geeks {

    // Main Method
    public static void Main(String[] args)
    {
        double a = Math.PI;

        // using Math.Asin() method
        Console.WriteLine(Math.Asin(a));

        // argument is greater than 1
        Console.WriteLine(Math.Asin(2));

        Console.WriteLine(Math.Asin(0.3584));

        double d = 0.0;
        double e = -0.0;
        double posi = Double.PositiveInfinity;
        double nega = Double.NegativeInfinity;
        double nan = Double.NaN;

        // Input positive zero
        // Output 0
        double res = Math.Asin(d);

        // converting to degree
        // i.e. output is 0 degree
        double rest = res * (180 / Math.PI);
        Console.WriteLine(rest);

        // Input negative zero
        // Output 0
        Console.WriteLine(Math.Asin(e));

        // input PositiveInfinity
        // Output NaN
        Console.WriteLine(Math.Asin(posi));

        // input NegativeInfinity
        // Output NaN
        Console.WriteLine(Math.Asin(nega));

        // input NaN
        // Output NaN
        Console.WriteLine(Math.Asin(nan));
    }
}

Output:

NaN
NaN
0.366553473829125
0
0
NaN
NaN
NaN

Reference: https://msdn.microsoft.com/en-us/library/system.math.Asin