O is the centre of the circle and P, Q and R are points on the circumference. What can you say about the angles a, b, c, d, e and f ? Give reasons for your answers.

Now suppose that the points P and R remain fixed and the point Q moves around the circumference of the circle. Make and prove some conjectures about the angles in the diagram.

What happens to the angles in the diagram if the points Q and R remain fixed and the point P moves around the circumference of the circle?

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