demo.svg

<?xml version="1.1" encoding="UTF-8" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" width="200" height="120">

  <!-- large arc -->
  <path d="M 50 20
    a 30 30 0 1 0 50 0
    " stroke="black" fill="green" stroke-width="2" fill-opacity="0.1"
    data-c-export="large-arc: a"
    data-c-constraints="a isFixed"
  />

  <!-- cone -->
  <path d="M 120 50
    a 15 15 1 0 1 0 -30
    l 60 15
    z
  " stroke="black" fill="maroon" stroke-width="2" fill-opacity="0.1"
    data-c-constraints="
      a isTangentWith large-arc
      (a.midpoint to l) isPerpendicularTo large-arc
    "
  />
</svg>