Treefolk, mathematical beings by terrance tao, precisely drawn, cleanly labeled image, penciled biological illustration, beautiful scientific diagram: when a treefolk makes its trunk vertical (or straight), it's cylindrical in shape, and has horizontal rings on its exterior at intervals of one inch apart; one easily calculates the height of a treefolk in inches by counting its rings. consider the treefolk’s trunk geometrically as a sequence of horizontal disks stacked on top of each other, with each disk being an inch in height and constant horizontal radius.