These two lines are parallel to each other and to the 90-270° axis and at right angles to the 0 -180° disc axis with the disc centre (screw) in the middle between them.
Le migca mibini iyafana kwaye iku 90°-270° ikwi mbombo ezilungileyo ezingu 0-180° wecwecwe kunye nomphakathi wecwecwe ophakathi kwazo