A, C and D are points on a circle, centre 0.
AB and CB are tangents to the circle.
Angle ABC = 74°
Work out the size of angle ADC.
Show your working clearly.

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.