Poincare disc model

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The JavaScript code

var brd = JXG.JSXGraph.initBoard('jxgbox',{boundingbox:[-5,5,5,-5]});
var c = brd.create('circle',[[0,0],3],{strokeColor:'black', fixed:true});  // outer circle

var p = brd.create('point',[0,-4],{withLabel:false});
var t = brd.create('polar', [c,p], {strokeColor:'gray', dash:2, visible:false}); 
var s1 = brd.create('intersection', [c,t,0], {withLabel:false, strokeColor:'green', fillColor:'green'}); 
var s2 = brd.create('intersection', [c,t,1], {withLabel:false, strokeColor:'green', fillColor:'green'}); 
var arc = brd.create('arc',[p,s1,s2],{name:'g', withLabel:true});

var pp = brd.create('point',[1,2],{withLabel:true,name:'P'});
var t = brd.create('polar', [c,pp], {visible:false}); 
var l = brd.create('line', [[0,0],pp], {visible:false}); 
var A = brd.create('intersection', [l,t,0], {withLabel:true,visible:false});
var M = brd.create('midpoint',[pp,A], {withLabel:true,visible:false});
var perp = brd.create('perpendicular', [l,M], {name:'', withLabel:false, strokeColor:'gray', dash:1, straightFirst:true, straightLast:true, point: {visible:true}});

var x = brd.create('glider',[3, 3, perp], {name:'drag me'});

var t2 = brd.create('polar', [c, x], {strokeColor:'gray', dash:2, visible:false}); 
var ss1 = brd.create('intersection', [c,t2,0], {withLabel:false, strokeColor:'green', fillColor:'green'}); 
var ss2 = brd.create('intersection', [c,t2,1], {withLabel:false, strokeColor:'green', fillColor:'green'}); 
var arc = brd.create('circumcirclearc',[ss1,pp,ss2], {strokeWidth:1, trace:true, dash:3});

References

  • Chaim Goodman-Strauss, "Compass and Straightedge in the Poincare Disk", Am. Math. Monthly 108 (2001), 38-49.