<Image xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
  <Image.Source>
    <DrawingImage>
      <DrawingImage.Drawing>
        <GeometryDrawing Brush="Orange">
          <GeometryDrawing.Pen>
            <Pen Brush="Black" Thickness="10"/>
          </GeometryDrawing.Pen>
          <GeometryDrawing.Geometry>
            <PathGeometry>
              <!-- Trójkąt #1 -->
              <PathFigure IsClosed="True">
                <LineSegment Point="0,100"/>
                <LineSegment Point="100,100"/>
              </PathFigure>
              <!-- Trójkąt #2 -->
              <PathFigure StartPoint="70,0" IsClosed="True">
                <LineSegment Point="0,100"/>
                <LineSegment Point="100,100"/>
              </PathFigure>
            </PathGeometry>
          </GeometryDrawing.Geometry>
        </GeometryDrawing>
      </DrawingImage.Drawing>
    </DrawingImage>
  </Image.Source>
</Image>