About Calculating Angle

Mayur Ghatkar

9y922

Hi,

I have an arc where I know start point, end point and center of arc. Now I want to calculate angle from start point to end point from center point. Its like calculating angle between two points of circle.

I searched for many links. I also tried math Math.Atan2 function but It not gives me expexted result that I want. Angle between 0 to 360. I want to calculate this value.

So please help me in this issue. Thanks for help in advanced.

2 Replies

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Ankit Sharma9y ago
Accepted answer
Hi Mayur,

Atan2 gives a result in the range -pi to +pi.* If you want a number in the range 0 to 2pi(360), just add 2pi if the result is less than 0.

after this you need to change radian value to degrees as shown here

https://stackoverflow.com/a/1311134

Hope this helps
Tapan Patel9y ago
It is euclidean vector.

try this.
created my class that represents point on the surface and had operator overloading that actually calculates the distance between two points ( not accurate representation for - between two points but for time being).
public class CirclePoints
      {
          public Point p;
          public CirclePoints(int x, int y)
          {
              p = new Point(x, y);
          }
          public static double operator-(CirclePoints p1,CirclePoints p2)
          {

              return Math.Sqrt(Math.Pow(p1.p.X - p2.p.X,2)+ Math.Pow(p1.p.Y - p2.p.Y, 2));


          }
      }
And in your main method.
CirclePoints p1 = new CirclePoints(5,0);
          CirclePoints p2 = new CirclePoints(0, 5);
          CirclePoints center = new CirclePoints(0, 0);
          double radius = p2-center;

          //do a rounding here for this formula
          double alpha = Math.Acos((2*Math.Pow(radius, 2) - Math.Pow(p1-p2, 2)) / (2 * Math.Pow(radius, 2)));


          var FinalAngle = alpha * (180 / Math.PI); // <-- output.