нарисовать фигуру с помощью С# в Silverlight в wp7

Я думаю, что это http://www.windowsphonegeek.com/tips/drawing-in-wp7-1-getting-started-and-line-shape поможет вам рисовать фигуры с помощью C#.

Ваш XAML:

<Canvas x:Name="ContentPanelCanvas" Grid.Row="1" Background="Transparent"  Margin="12,0,12,0">
    <Line X1="10" Y1="100" X2="150" Y2="100" Stroke="Green" StrokeThickness="5"/>
</Canvas>

C#:

Line line = new Line();
line.Stroke = new SolidColorBrush(Colors.Purple);
line.StrokeThickness = 15;

Point point1 = new Point();
point1.X = 10.0;
point1.Y = 100.0;

Point point2 = new Point();
point2.X = 150.0;
point2.Y = 100.0;

line.X1 = point1.X;
line.Y1 = point1.Y;
line.X2 = point2.X;
line.Y2 = point2.Y;

this.ContentPanelCanvas.Children.Add(line);