WPF中从中心点到特定点的路径、弧段计算

我在XAML中定义了弧段，在代码中，我需要计算从弧的中心点到特定Y点的Y值。请看图片以便更好地理解

XAML

 <Canvas Name="canvas" Background="White" Opacity="99">
        <Path Stroke="Red" MouseLeftButtonDown="Path_MouseLeftButtonDown">
            <Path.Data>
                <PathGeometry>
                    <PathFigureCollection>
                        <PathFigure StartPoint="250,250">
                            <ArcSegment Size="70,70" IsLargeArc="True" SweepDirection="Counterclockwise" Point="250,200"/>
                        </PathFigure>
                    </PathFigureCollection>
                </PathGeometry>
            </Path.Data>
        </Path>
       
    </Canvas>

屏幕截图

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中心的y值是起点和终点y值的平均值（因为它们的x值相同），即225。减去70是155，不是154。嗨，克莱门斯，非常感谢你！这解决了我的问题。确实是155。我只是依靠我的鼠标指针。我的公式是var meanY=（yStart+扫掠角）/2-70；中心的y值是起点和终点y值的平均值（因为它们的x值相同），即225。减去70是155，不是154。嗨，克莱门斯，非常感谢你！这解决了我的问题。确实是155。我只是依靠我的鼠标指针。我的公式是var meanY=（yStart+扫掠角）/2-70；

//I got this from StackOverflow maybe someone can figure out for the correct computation.
     private void Path_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
            {
                var curve = sender as Path;
                var geometry = curve.Data as PathGeometry;
                var figure = geometry.Figures.FirstOrDefault();
                var arcSegment = figure.Segments.FirstOrDefault() as ArcSegment;
                var xStart = figure.StartPoint.X;
                var yStart = figure.StartPoint.Y;
                var startAngle = arcSegment.Point.X;
                var sweepAngle = arcSegment.Point.Y;
                var Rx = arcSegment.Size.Width; // this is radius width
                var Ry = arcSegment.Size.Height;  // this is radius height
                var centerX = xStart - Rx * Math.Cos(startAngle);
                var centerY = yStart - Ry * Math.Sin(startAngle);
                var endAngle = startAngle + sweepAngle;
                var xEnd = centerX + Rx * Math.Cos(endAngle);
                var yEnd = centerY + Ry * Math.Sin(endAngle);
            }