Create a polyline with a PathGeometry
<Window x:Class="RadialGradientBrushExample"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Radial Gradient" Height="320" Width="368">
<Canvas>
<Path Stroke="Blue">
<Path.Data>
<PathGeometry>
<PathFigure StartPoint="100,120">
<PolyLineSegment Points="200,120,200,220,100,170" />
</PathFigure>
</PathGeometry>
</Path.Data>
</Path>
</Canvas>
</Window>
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