How can I make a rounded corner triangle in XAML-Silverlight?
I think the below Path will solve your problem, Only you need to change the points of your triangle according to your requirement. For more idea about Path
<Path Data="M 300 100 L 500 400 100 400 Z"
StrokeThickness="48"
StrokeLineJoin="Round"
Stroke="Blue"
Fill="Blue" />