10 (a) AC and BD are diameters of the circle, centre O. Show that triangle ABC is congruent to triangle BAD. Give a reason for each statement you make. (b) Two tangents, TC and TD, are drawn to the circle in part (a). The diameter of the circle is 8 cm and ABDˆ = 28°. (i) Find CODˆ. (ii) Calculate the area shown shaded in the diagram.