Perpendicular to chord

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

var p1 = board.create('point', [0, 2.0],{name:'O',face:'',label:{offset:[-10,5]}});
var c1 = board.create('circle', [p1, 6],);
var g1 = board.create('glider', [-1.0, 4, c1],{face:'',label:{offset:[-10,10]}});

var g2 = board.create('glider', [1.0, 2.2, c1],{face:'',label:{offset:[5,-5]}});

var l1 = board.create('segment', [g1, g2]);

var pp1 = board.create('perpendicularpoint', [p1, l1],{face:''});
var l2 = board.create('segment', [p1, pp1]);
var a1 = board.create('angle', [g1, pp1, p1],{radius:1,name:' '});