Properties of an ellipse

						JXG.Options.text.useKatex = true;
JXG.Options.axis.ticks.majorHeight = 10;
JXG.Options.axis.ticks.insertTicks = false;
JXG.Options.axis.ticks.ticksDistance = 100;
var board = JXG.JSXGraph.initBoard('box1', {
boundingbox:[-10, 10, 10, -10],showNavigation:false, showcopyright: false, axis: true,
});

 var F1 = board.create('point', [-6,0],{name:'F1',fixed:true, label:{offset:[-40,10]}});
var F2 = board.create('point', [function(){return -F1.X()},function(){return F1.Y();}],{name:'F2',label:{offset:[-40, -15]}});
var p1 = board.create('point', [1,3],{name:'',size:0,fixed:true});
var el = board.create('ellipse',[F1,F2,p1],{strokeColor:'red'});
var g1 = board.create('glider', [2.0, 1.5, el],{name:'P'});
var l1 = board.create('segment', [F1, g1],{strokeWidth:1});
var l2 = board.create('segment', [F2, g1],{strokeWidth:1});
var x1 =  board.create('point', [1,0],{visible:false});
var x2 =  board.create('point', [5,0],{visible:false});
var cx = board.create('line', [x1,x2],{visible:false});
var i1 = board.create('intersection', [cx, el],{visible:false});
var i2 = board.create('intersection', [cx, el,1],{visible:false});
var j1 =  board.create('point', [function(){return i1.X()},-8],{visible:false});
var j2 =  board.create('point', [function(){return i2.X()},-8],{visible:false});
var l3 = board.create('segment', [i1, j1],{strokeWidth:1});
var l4 = board.create('segment', [i2, j2],{strokeWidth:1});
 
var pa1 = board.create('point', [function(){return i2.X()}, -7],{name:'',size:0});
var pa2 = board.create('point', [function(){return i2.X()+5.5}, -7],{name:'',size:0});
var l5 = board.create('arrow', [pa2, pa1],{strokeWidth:1});

board.create('text',[function(){return i2.X()+6},-7, function(){ return "2a";}],{fontSize: 11},{strokeWidth:1});
var pa3 = board.create('point', [function(){return i2.X()+8}, -7],{name:'',size:0 });
var pa4 = board.create('point', [function(){return i1.X()}, -7],{name:'',size:0});
var l6 = board.create('arrow', [pa3, pa4],{strokeWidth:1});
var k1 =  board.create('point', [function(){return F1.X()},-6],{visible:false});
var k2 =  board.create('point', [function(){return F2.X()},-6],{visible:false});
var l7 = board.create('segment', [F1, k1],{strokeWidth:1});
var l8 = board.create('segment', [F2, k2],{strokeWidth:1});

var pc1 = board.create('point', [function(){return F1.X()}, -5],{name:'',size:0});
var pc2 = board.create('point', [function(){return F1.X()+5.5}, -5],{name:'',size:0});
var l9 = board.create('arrow', [pc2, pc1],{strokeWidth:1});

board.create('text',[function(){return F1.X()+6},-5, function(){ return "2c";}],{fontSize: 11});
var pc3 = board.create('point', [function(){return F1.X()+8}, -5],{name:'',size:0 });
var pc4 = board.create('point', [function(){return F2.X()}, -5],{name:'',size:0});
var l10 = board.create('arrow', [pc3, pc4],{strokeWidth:1});
var y1 =  board.create('point', [0,1],{visible:false});
var y2 =  board.create('point', [0,-1],{visible:false});
var cy = board.create('line', [y1,y2],{visible:false});
var iy1 = board.create('intersection', [cy, el],{visible:false});
var iy2 = board.create('intersection', [cy, el,1],{visible:false});  

var m1 =  board.create('point',[9, function(){return iy1.Y()}],{name:'',size:0});
var m2 =  board.create('point',  [9, function(){return iy2.Y()}],{name:'',size:0});
var l3 = board.create('segment', [iy1, m1],{strokeWidth:1});
var l4 = board.create('segment', [iy2, m2],{strokeWidth:1});

var pb1 = board.create('point', [8, function(){return iy1.Y()-2}],{name:'',size:0});
var pb2 = board.create('point', [8, function(){return iy1.Y() }],{name:'',size:0});
board.create('text',[7.6,function(){return iy1.Y()-3}, function(){ return "2b";}],{fontSize: 11}); 
 
var pb3 = board.create('point', [8, function(){return iy1.Y()-4}],{name:'',size:0});
var pb4 = board.create('point', [8, function(){return iy2.Y() }],{name:'',size:0});
var l11 = board.create('arrow', [pb1, pb2],{strokeWidth:1});
var l12 = board.create('arrow', [pb3, pb4],{strokeWidth:1});
var C = board.create('intersection', [cx, cy],{name:'C'});