(i) XYZ = 180 - 64
= 116 degrees
Opposite angles in a cyclic quadrilateral add up to 180 degrees
(ii) YXZ = 23 degrees
Alternate angles in a segment are the same
(iii) OXZ = 26
XOZ = 64 x 2
= 128 degrees
The the angle at the centre is double the angle at the circumference.
180 - 128 = 52
OXZ = 52/2
= 26
Triangle OZX is an isosceles triangle
(Don't forget to include the reasons above full marks)