Using ruler and a pair of compasses only, 

(a) construct, (i) triangle XYZ with |XY| = 8cm, < YXZ = 60° and < XYZ = 30° ; (ii) the perpendicular ZT to meet XY in T ; (iii) the locus \(l_{1}\) of points equidistant from ZY and XY.

(b) If \(l_{1}\) and ZT intersect at S, measure |ST|.