Show that the diameter of the inscribed circle of a triangle

						var board = JXG.JSXGraph.initBoard('box1', {
boundingbox: [-10, 9, 10, -11],showNavigation:false, showcopyright: false, axis: false,
});

var p1 = board.create('point', [-7, 0],{face:'',name:''});
var p2 = board.create('point', [1.5, 7.5],{face:'',name:''});
var p3 = board.create('point', [6, 0],{face:'',name:''});
var l1 = board.create('segment', [p1, p2]);
var l2 = board.create('segment', [p2,p3]);
var l3 = board.create('segment', [p1, p3],{withlabel:true,name:'a',label:{offset:[0,-10]}});

var ic1 = board.create('incircle', [p1, p2, p3]);
var ice1 = board.create('incenter', [p1, p2, p3],{face:'',name:'O',label:{offset:[-5,-12]}});
var perp1 = board.create('perpendicularsegment', [l1, ice1],{withlabel:true,name:'r',color:'blue',label:{offset:[-10,20]}});
var perp2 = board.create('perpendicularsegment', [l2, ice1],{withlabel:true,name:'r',color:'blue',label:{offset:[-20,0]}});
var pl1 = board.create('parallel', [l3, ice1],{visible:false});
var i1 = board.create('intersection', [l1, pl1],{name:'M',face:'',label:{offset:[-10,10]}});
var i2 = board.create('intersection', [l2, pl1],{name:'N',face:''});
var l1 = board.create('segment', [i1, i2]);