A 5-circle incidence theorem
From JSXGraph Wiki
<jsxgraph width="600" height="600"> var brd = JXG.JSXGraph.initBoard('jxgbox',{boundingbox:[-5,5,5,-5]}); var A = [], s = [], B = [], k;
var attA = {name:,strokeColor:'#7355ff',fillColor:'#7355ff'}; A[0] = brd.create('point',[-2.5,-3], attA); A[1] = brd.create('point',[-0,4], attA); A[2] = brd.create('point',[2.5,-3], attA); A[3] = brd.create('point',[-4,0], attA); A[4] = brd.create('point',[4,0], attA);
for (k = 0; k < 5; k++) {
s[k] = brd.create('segment',[A[k], A[(k + 2) % 5]],{strokeColor:'blue',strokeWidth:1});
}