This is a ruler element.
<ruler-element pie-id="1"></ruler-element>

And here is a triangle you can play with:
<div style="width: 300px">
  <svg viewBox="0 0 100 100">
    <path d="M 0,0 l 50,50 l 50,-50  l 0,0 z" fill="lightgreen"></path>
  </svg>
</div>