A trangle with dynamic points on two sides and forming an isosceles triagnle

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

var p1 = board.create('point', [-8, -5],{name:'B',face:'',fixed:true,label:{offset:[-15,10]}});
var p2 = board.create('point', [6, -5],{name:'C',face:'',fixed:true});
var p3 = board.create('point', [3, 6],{name:'A',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 g1 = board.create('glider', [-6.0, 1, l3],{name:'E',label:{offset:[-15,10]}});
var l4 = board.create('segment', [p1, g1],);
var L2 = l2.L();

var sinB = (p3.Y()-p2.Y())/L2;
var cosB = (p2.X()-p3.X())/L2;
 
var p4 = board.create('point', [function(){return p2.X()-l4.L()*cosB;}, function(){return l4.L()*sinB+p2.Y()}],{face:''});
var l5 = board.create('segment', [g1, p2],);
var l6 = board.create('segment', [p1, p4],);
var i1 = board.create('intersection', [l5, l6],{name:'O',face:'',label:{offset:[-2,10]}});