Prove that a cyclic rhombus is a square.

In the figure which circles are congruent to the circle $A$.

What measure of the circles make them congruent?

Name the part $\overline{\mathrm{AO}}$ from the adjacent figure where $\text{'}\mathrm{O}\text{'}$ is the centre of the circle.

Name the part $\overline{\mathrm{AB}}$ from the adjacent figure where $\text{'}\mathrm{O}\text{'}$ is the centre of the circle.