(a) The sum of the interior angles of a regular polygon is 900°. Find the number of sides of the polygon.

(4b) Using a ruler and a pair of compasses only, construct:
(i)Triangle XYZ such that the length XY = 10cm, angle XYZ = 30 degrees and length YZ = 9cm:
(ii) Perpendicular line from Z to meet line XY at P
(iii) measure the (1) length PZ (2) Angle XZY
(iv) Calculate,correct to the nearest whole number,the area of triangle XYZ