Chigongono cha digirii 90 ndi mtundu wa chigongono chokhala ndi ngodya ya madigiri 90, omwe amagwiritsidwa ntchito makamaka kusintha mayendedwe a payipi.Nthawi zambiri amagwiritsidwa ntchito m'mapaipi omwe amakhotakhota mwamphamvu amafunikira, monga ngati zida zina zamapaipi ziyenera kulumikizidwa isanayambe kapena itatha kupindika.
