docs: def triangle(rad=0.5):
      """Draw a triangle"""
      # half_height = math.sqrt(3) * side / 6
      # half_height = side / 2
      ctx = _state["ctx"]
      side = 3 * rad / math.sqrt(3)
      ctx.move_to(0, -rad / 2)
      ctx.line_to(-side / 2, -rad / 2)
      ctx.line_to(0, rad)
      ctx.line_to(side / 2, -rad / 2)
      ctx.close_path()
      ctx.fill()