Setsoe sa 90 degree ke mofuta oa setsoe o nang le angle ea likhato tse 90, haholo-holo o 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 kamora ho kobeha.
