9.1 In the diagram O is the centre of the circle and ABC are points on the circle. Use the diagram in your SPECIAL ANSWER BOOK to prove that:AÔB = 2AĈB.
9.2 In the figure below, DĈO = 25° and O is the centre of the circle. A, B, E C and D are points on the circumference. Calculate, giving reasons, the sizes of:
9.2.1 D̂1 (2)
9.2.2 Ô1 (2)
9.2.3 Â1 (2)
9.2.4 Ê (2)