SVG Circle in D3JS

 svg.append("circle")

    .attr("cx", 200)

    .attr("g", 100)

    .attr("r", 50);

SVG path in D3JS

 svg.append("path")

    .style("stroke", "black")

    .style("fill","none")

    .attr("d", "M 100, 50, L 200, 150, L 300, 50 Z");

//output will be Upside down triangle