Congruent right triangles share the same side with one internal angle 60 degrees

						var board = JXG.JSXGraph.initBoard('box1', {
boundingbox: [-10, 10, 10, -10],showNavigation:false, showcopyright: false, axis: false,
});
var p1 = board.create('point', [-4, -2.0],{face:''});
var p2 = board.create('point', [-4, 4.0],{face:''});
var pol1 = board.create('regularpolygon', [p2, p1, 3]);
 pol1.vertices[2].setAttribute({name:' ',face:''})
var mp1 = board.create('mirrorpoint', [p1, pol1.vertices[2]],{face:''});
var mp2 = board.create('mirrorpoint', [p2, pol1.vertices[2]],{face:''});
var l1 = board.create('segment', [p1, mp2]);
var pol2 = board.create('polygon', [mp1, mp2, pol1.vertices[2]],);
var a1 = board.create('angle', [p1, pol1.vertices[2], mp2],{radius:1});

var a2 = board.create('angle', [p1,p2, mp2],{radius:1,name:'60°',label:{offset:[-8,0]}});