4 (a) ACD is a triangle and ADCˆ = 110°. EB is parallel to DC and AE = EB. (i) Find x, giving reasons for each step in your working. (ii) Given that EB = 12 cm and DC = 20 cm, find ED. (b) Find the value of a. (c) P, Q, R and S are vertices of a regular polygon. M is the midpoint of PR. PQ = 14 cm and QM = 7 cm. How many sides has the polygon? Show your working.