Setsoe sa 90 degree ke mofuta oa setsoe se nang le angle ea likhato tse 90, haholo-holo se sebelisetsoang ho fetola tsela ea phallo ea phaephe. Hangata e sebelisoa litsamaisong tsa liphaephe moo ho hlokahalang li-angles tse thata tse kobehang, joalo ka ha lisebelisoa tse ling tsa liphaephe li hloka ho hokeloa pele kapa ka mor'a ho kobeha.
