XXX, Y Y\,Y and Z Z\,Z are points on the circumference of a circle, centre OOO. WY WY\,WY and WZ WZ\,WZ are tangents to the circle from an external point WWW.
Angle OWZ=19∘OWZ = 19^\circOWZ=19∘
Find the size of angle YXZYXZYXZ.
Give reasons for each stage of your working.
