JAMB Mathematics 2018 Paper

Concept:A locus is the set of all points that satisfy a given geometric condition.Explanation:The given condition is that every point must remain exactly $4\text{ cm}$ away from the fixed point P.As a point moves around P while keeping this distance constant, it traces out a path.Along this path, the distance from P never changes; it is always $4\text{ cm}$.The set of all points at a fixed distance from a single centre is a circle.Here, P is the fixed centre, and the fixed distance is the radius.Therefore, the radius is $4\text{ cm}$.This is not a straight line, a perpendicular line, or a circle with diameter $4\text{ cm}$.A circle with diameter $4\text{ cm}$ would have radius only $2\text{ cm}$, which does not match the given distance.Hence, the required locus is a circle centred at P with radius $4\text{ cm}$.Answer:A circle of radius $4\text{ cm}$ from point P.