Construction: Join point O and X together to produce OX\[\begin{align}  & OZ=OX\text{   }\{Radius\text{ }of\text{ }circle\} \\ & \angle XZM=\angle ZOM={{25}^{\circ }}\text{   }\!\!\{\!\!\text{ alternate angles }\!\!\}\!\!\text{ } \\ & \angle OZX=\angle OXZ\text{  }\!\!\{\!\!\text{ Base }\angle s\text{ of Isso }\vartriangle \text{ }\!\!\}\!\!\text{ } \\ & \angle ZOX={{180}^{\circ }}-\angle OZX-\angle OXZ\text{  }\!\!\{\!\!\text{ }\angle \text{s in a }\vartriangle \text{ }\!\!\}\!\!\text{ } \\ & \angle ZOX={{180}^{\circ }}-{{25}^{\circ }}-{{25}^{\circ }}={{130}^{\circ }} \\ & \angle XYZ=\tfrac{1}{2}\angle ZOX\text{   }\!\!\{\!\!\text{ }\angle \text{ at circumference}=\tfrac{1}{2}\times \angle \text{ at centre }\!\!\}\!\!\text{ } \\ & \angle XYZ=\tfrac{1}{2}({{130}^{\circ }})={{65}^{\circ }} \\\end{align}\]