Abcd is a trapezium in which ab ll bc and ad = bc, prove that
(i) ∠a = ∠b (ii) ∠c = ∠d (iii) δabc ≅ δbad (iv) ac = bd

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.