(a(i))[2]
Using compasses and a straight edge, construct the perpendicular bisector of $AC$.
(a(ii))[1]
Find the locus of points that are the same distance from $AB$ and $AC$.
(b)[1]
The perpendicular bisector of $AC$ cuts $BC$ at $P$. $Q$ is the point on $BC$ that is equally distant from $AB$ and $AC$. Mark and label $P$ and $Q$ on the diagram, then measure $PQ$.