Trace curve

The underlying JavaScript code

var brd = JXG.JSXGraph.initBoard('jxgbox',{axis:false,boundingbox:[-2,2,2,-2],keepaspectratio:true});
var A = brd.create('point', [-1.5, -1.5]);
var B = brd.create('point', [1.5, -1.5]);
var C0 = brd.create('point', [1.5, 1.0], {visible:false});
var g = brd.create('line', [A,B], {visible:false});
var h = brd.create('parallel', [g, C0], {visible:true, strokeWidth:1});
var C = brd.create('glider', [-1.5, 1.0, h], {name:'C'});
var p = brd.create('polygon', [A, B, C]);

var s1 = brd.create('perpendicular', [p.borders[0], C], {dash:3, strokeWidth:1});
var s2 = brd.create('perpendicular', [p.borders[1], A], {dash:3, strokeWidth:1});
var s3 = brd.create('perpendicular', [p.borders[2], B], {dash:3, strokeWidth:1});

var S = brd.create('intersection', [s1, s2, 0], {name:'S', trace:false});
var curve = brd.create('tracecurve', [C, S], {strokeColor:'blue'});