A trangle with bisector of one internal angle and auxiliary line

						var board = JXG.JSXGraph.initBoard('box1', {
boundingbox: [-10, 10, 10, -10],showNavigation:false, showcopyright: false, axis: false,
});

var p1 = board.create('point', [1.5, -4],{face:'',fixed:true});
var p2 = board.create('point', [-9, -4],{face:'',fixed:true,label:{offset:[-10,10]}});
var p3 = board.create('point', [-2.5, 2.0],{face:'',fixed:true});
var l1 = board.create('segment', [p1, p2]);
var l2 = board.create('segment', [p2, p3]);
var l3 = board.create('segment', [p3, p1]);
var bi1 = board.create('bisector', [p1, p3, p2],{visible:false});
var i1 = board.create('intersection', [bi1, l1],{face:'',label:{offset:[-15,10]}});
var l4 = board.create('segment', [p3, i1]);
//CD^2=CB.CE
var m=l4.L()*l4.L()/(l2.L());
var k = l3.getSlope();
var ang = Math.PI+Math.atan(k) //+Math.PI/2
 
var x = p3.X()-m*Math.cos(ang)
var y = p3.Y()-m*Math.sin(ang)
var p4 = board.create('glider', [x, y,l3],);
var l5 = board.create('segment', [i1, p4],{dash:2});