Geometry & measures · Constructions & loci
Chapter 1 · 3
The idea
Loci & regions
A locus as the set of points obeying a rule, the four standard loci, and how to combine several conditions — with scale drawings — to shade the region that satisfies all of them at once.
A full journey — read it, play with it, work it, then earn real exam marks. Everything stays on the timeline below.
In this lesson — start anywhere
Geometry & measures · Constructions & loci
Loci & regions
A locus as the set of points obeying a rule, the four standard loci, and how to combine several conditions — with scale drawings — to shade the region that satisfies all of them at once.
Why it works
Every point that obeys the rule
A locus is simply "every point that obeys the rule". Ask *which points qualify?* and the shape draws itself. Four rules cover almost every GCSE question:| Rule | Locus |
|---|---|
| A fixed distance from a point | a circle, centre , radius |
| A fixed distance from a line segment | a racetrack: two parallel lines away, joined by semicircular ends |
| Equidistant from two points and | the perpendicular bisector of |
| Equidistant from two lines | the angle bisector between them |
Keep reading — free
The rest of the explanation, plus 2 worked examples you step through move by move.
Start freeTakes a minute — no card.