Locus and construction
When a person moves so that they always satisfy a certain condition, their
possible path is called a locus. For example, consider the path of a person who
walks around a building, always keeping the same distance away from the
building.
The dotted line in the diagram shows the path taken – i.e. the locus.
Need to learn:
1. The locus of a point which is always at a given distance 𝒓𝒓 from a given
point O is a circle with centre O and radius 𝒓𝒓.
2. The locus of a point which is always equidistant from two given points A
and B is the perpendicular bisector of AB.
3. The locus of a point which is always equidistant from two given
intersecting straight lines is the straight line which bisects the angle
between two given lines.
4. The locus of a point which is always 𝒅𝒅 cm from a given straight line AB
are the two parallel lines to AB at a distance of 𝒅𝒅 cm from AB and two
semi circle of radius 𝒅𝒅 cm centre A and B.
Anwar Sir
Senior Teacher of Mathematics, BAF SEMS