XY being on the circumference, the triangle so formed by joining X and Y to O is isosceles, therefore two sides and two angles are equal.
UX noY kuba besemdeni, unxantathu wenziwe ngokudibanisa uX kunye noY ukuya kuO banamacala amabini alinganayo ngobude, ngoko ke amacala amabini nembombo ezimbini ziyalingana.