In the diagram, $\mathrm{A}, \mathrm{B}, \mathrm{C}$ and $\mathrm{D}$ are points on the circumference of a circle with centre O. CD is a diameter of the circle, $\mathrm{AOO}=50^{\circ}$ and $\mathrm{OA}$ is parallel to $\mathrm{CB}$.

(i) Find $\mathrm{OCA}$.

(ii) Find OÂD.

(iii) Find $\mathrm{ABC}$.

(iv) Find $\mathrm{CAB}$.