function polarToCartesian(centerX, centerY, radius, angleInDegrees) {
  var angleInRadians = (angleInDegrees - 90) * Math.PI / 180.0;
  return {
    x: centerX + (radius * Math.cos(angleInRadians)),
    y: centerY + (radius * Math.sin(angleInRadians))
  };
}
function describeArc(x, y, radius, startAngle, endAngle) {
  var start = polarToCartesian(x, y, radius, endAngle);
  var end = polarToCartesian(x, y, radius, startAngle);
  var arcSweep = endAngle - startAngle <= 180 ? "0" : "1";
  var d = [
    "M", start.x, start.y,
    "A", radius, radius, 0, arcSweep, 0, end.x, end.y
  ].join(" ");
  return d;
}
$('#path').attr("d", describeArc(100, 100, 50, 0, 180));
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<svg width="200px" height="200px" version="1.1" xmlns="http://www.w3.org/2000/svg">
  <path id='path' fill="transparent" stroke='red' stroke-width='6' />
  <text x="100" y="100" transform="translate(0, 15)" font-family="Verdana" font-size="50" fill="blue" text-anchor='middle'>5</text>
  <circle cx="100" cy="100" fill="black" r="2" />
  <circle cx="100" cy="50" fill="black" r="2" />
</svg>