private static double GetAngle(IUtils utils, Point firstPoint, Point secondPoint) { var angle = utils.GetAngle(firstPoint, secondPoint); // convert to proper Cartesian angle of rotation angle = (450 - angle) % 360; // convert to Radians angle = angle * Math.PI / 180.0; // Get perpendicular angle: angle += 90 * Math.PI / 180.0; if (angle > 2 * Math.PI) { angle -= 2 * Math.PI; } return(angle); }