WAEC Mathematics 2013 Paper

Concept:The locus of a point that subtends a fixed angle at two fixed points is an arc of a circle.Explanation:$P$ and $M$ are fixed points and $X$ moves in the plane.Given $\angle PXM = 30^\circ$, the segment $PM$ always subtends a constant angle at $X$.For a fixed chord $PM$, all points $X$ that see the chord under the same angle lie on the same circular arc.Hence, $X$ moves along an arc of a circle with $PM$ as its chord.Answer:B. an arc of a circle with PM as a chord