SVG Marker

   <marker id="Tri" viewBox="0 0 10 10" refX="0" refY="5"  
        markerUnits="strokeWidth" markerWidth="6" 
        markerHeight="6" orient="auto">  
      <path d="M 0 0 L 10 5 L 0 10 z" />   
   </marker>  
   <polyline fill="none" stroke="darkred" stroke-width="5" 
      marker-end="url(#Tri)"  
      points="0,400 100,250 225,300 300,150 400,200 500,275 525,210" />