Point <i>T</i>  is the <a href="https://en.wikipedia.org/wiki/Centre_(geometry)" class="extiw" title="w:Centre (geometry)">center</a> of the circumcircle of <i>AEDFBC</i>  and  <i>ABCDEF.</i>  The first one <a href="https://en.wiktionary.org/wiki/regular_polygon" class="extiw" title="wiktionary:regular polygon">is regular</a> and <a href="https://en.wikipedia.org/wiki/Convex_set" class="extiw" title="w:Convex set">convex</a>, the second one is neither convex <a href="https://en.wikipedia.org/wiki/Simple_polygon" class="extiw" title="w:Simple polygon">nor simple.</a>  The two hexagons, that share all their <a href="https://en.wiktionary.org/wiki/vertices" class="extiw" title="wiktionary:vertices">vertices</a>, are <a href="https://en.wikipedia.org/wiki/Point_reflection" class="extiw" title="w:Point reflection">symmetric</a> with respect to <i>T.</i>  This point is called the center of the hexagons.<br> 
<a href="//commons.wikimedia.org/wiki/User:Baelde" title="User:Baelde">Baelde</a>
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