 Graph these items.
  document.body.appendChild(this.graph([
    "2D CGA - drag p1,p2,p3","",             // title
    ()=>"|D,p1|="+dp1,                       // distance
    ()=>"&beta; = "+beta,                    // distance
    0xFF8888, C, D, "D",                // circles
    0x44AA44, X, "X", Y, "Y",                // lines
    0x4444FF, pp1, "pp1", pp2, pp3,          // point pairs
    0x448844,
    ()=>position(C), ()=>"C "+(Math.sqrt(-radius(C)).toFixed(2)),
    ()=>position(D), ()=>"D "+(Math.sq