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C# / .NET - Math.Atan() method example

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Created by:

Trenton-McKinney

618

The Math.Atan function returns number in radians in the range -Math.PI/2 to +Math.PI/2. The function calculates the inverted tangent function value.

xxxxxxxxxx
 
using System;
​
public class Program
{
    static double CalculateAngle(double a, double b)
    {
        return Math.Atan(a / b);
    }
​
    public static void Main(string[] args)
    {
        /*
          |\
          | \ h
        a |  \
          |__*\ <- angle
            b
        */
​
        double a, b;
​
        // a an b build isosceles right triangle
        a = 3;
        b = a;
        Console.WriteLine(  CalculateAngle(a, b)); // 0.7853981633974483 <- ~45 degrees
​
        // a and b build half of equilateral triangle
        a = 3;
        b = a * Math.Sqrt(3);
        Console.WriteLine(  CalculateAngle(a, b)); // 0.5235987755982988 <- ~30 degrees
​
        // a and b build very high (+Inf) and slim (~0) triangle
        a = Double.PositiveInfinity;
        b = 0;
        Console.WriteLine(  CalculateAngle(a, b)); // 1.5707963267948966 <- ~90 degrees
    }
}

1. Documentation

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Syntax	xxxxxxxxxx 1 namespace System 2 { 3 public static class Math 4 { 5 // ... 6 public static double Atan(double number) { ... } 7 // ... 8 } 9 }
Parameters	`number` - double number value that represents the result of the operation `opposite / adjacent` on the right triangle (primitive value).
Result	`number` value in radians in the range `-Math.PI/2` to `+Math.PI/2` (primitive value). If value can not be calculated `NaN` is returned.
Description	`Atan` is a static method that takes only one parameter and returns an approximation of the result of the mathematical function arctangent(x).

2. Working with degrees

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xxxxxxxxxx
 
using System;
​
public class Program
{
    static double CalculateAngle(double a, double b)
    {
        double angle = Math.Atan(a / b);
​
        return (180 / Math.PI) * angle; // rad to deg conversion
    }
​
    public static void Main(string[] args)
    {
        /*
          |\
          | \ h
        a |  \
          |__*\ <- angle
            b
        */
​
        double a, b;
​
        // a an b build isosceles right triangle
        a = 3;
        b = a;
        Console.WriteLine(CalculateAngle(a, b)); // ~45 degrees
​
        // a and b build half of equilateral triangle
        a = 3;
        b = a * Math.Sqrt(3);
        Console.WriteLine(CalculateAngle(a, b)); // ~30 degrees
​
        // a and b build very high (+Inf) and slim (~0) triangle
        a = Double.PositiveInfinity;
        b = 0;
        Console.WriteLine(CalculateAngle(a, b)); // ~90 degrees
    }
}