Locus of a point
Loci, which is plural to locus, is reffered to the plotting of any path in a geometric construction. A locus of a point could be as simple as plotting the path of a tennis ball as it bounces on the floor, to very complex loci of mechanisms. It is important to note that when we plot a path we do that against time, so one could keep in mind that each point is like a snapshot and when we superimpose the snapshots the loci is revealed.
Video of tennis ball bouncing on the floor.
We have 4 special loci called The Involute, The Cycloid, The Helix and the Archimedean Spiral. It is important to study well the characteristics of each and every one as some are very similar to each other. You can find below the notes for these 4 special loci.