C# 两条线获取角度，角度原点距离获取另一点

    // 获得鼠标点击位置和原点组成的线与原点垂线的角度
    private double GetAngel()
    {
        int X = Convert.ToInt32(numericUpDown1.Value);
        int Y = Convert.ToInt32(numericUpDown2.Value);
        Point pictureBox1Point = pictureBox1.PointToClient(Control.MousePosition);
        Point a1 = new Point(X, Y);
        Point a2 = new Point(X, 300);
        Point b1 = new Point(X, Y);
        Point b2 = new Point(pictureBox1Point.X, pictureBox1Point.Y);
        var a = Math.Atan2(a2.Y - a1.Y, a2.X - a1.X);
        var b = Math.Atan2(b2.Y - b1.Y, b2.X - b1.X);
        double angle = 180 * (b - a) / Math.PI;
        return (angle  0  angle : angle + 360);
    }
    /// summary
    /// 通过三角函数求终点坐标
    /// /summary
    /// param name="angle"角度/param
    /// param name="startPoint"起点/param
    /// param name="distance"距离/param
    /// returns终点坐标/returns
    private static double[] getEndPointByTrigonometric(double angle, double[] startPoint, double distance)
    {
        double[] endPoint = new double[2];
        //角度转弧度
        double radian = (angle * Math.PI) / 180;
        //计算新坐标 r 就是两者的距离
        endPoint[0] = startPoint[0] + distance * Math.Cos(radian);
        endPoint[1] = startPoint[1] + distance * Math.Sin(radian);
        return endPoint;
    }
    // 根据角度和原点垂线画线的方法
    private void SettingOutByAngel(Graphics g, float angel)
    {
        float X = Convert.ToInt32(numericUpDown1.Value);
        float Y = Convert.ToInt32(numericUpDown2.Value);
        g.TranslateTransform(X, Y);
        g.RotateTransform(angel + 90);
        g.DrawLine(new Pen(Color.Red), 0, 0, 300, 0);
        g.ResetTransform();
    }