C# | Math.Acos() Method

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

Syntax:

public static double Acos(double num)

Parameter:

num: It is the number that represents cosine 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 0 ≤ Θ ≤ π.

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.

Examples:

Input  : Math.Acos(2)
Output : NaN

Input  : Math.Acos(0.3584)
Output : 1.20424285296577

Input  : Math.Acos(0.0)
Output : 1.5707963267949

Input  : Math.Acos(-0.0)
Output : 1.5707963267949

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

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

Program: To illustrate the Math.Acos() method

 // C# program to demonstrate working // of Math.Acos() method using System;    class Geeks {        // Main Method     public static void Main(String[] args)     {         double a = Math.PI;            // using Math.Acos() method         Console.WriteLine(Math.Acos(a));            // argument is greater than 1         Console.WriteLine(Math.Acos(2));            Console.WriteLine(Math.Acos(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 1.5707963267949         double res = Math.Acos(d);            // converting to degree         // i.e output will be 90 degree         double rest = res * (180 / Math.PI);         Console.WriteLine(rest);            // Input negative zero         // Output 1.5707963267949         Console.WriteLine(Math.Acos(e));            // input PositiveInfinity         // Output NaN         Console.WriteLine(Math.Acos(posi));            // input NegativeInfinity         // Output NaN         Console.WriteLine(Math.Acos(nega));            // input NaN         // Output NaN         Console.WriteLine(Math.Acos(nan));     } }

Output:

NaN
NaN
1.20424285296577
90
1.5707963267949
NaN
NaN
NaN

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