You will need to be able to use straight edge and a pair of compasses to carry out constructions. Below, the steps for a standard construction are described and an interactive illustration of the construction is shown.
Summary/Background
A locus is a rule that describes where a point can be positioned on a graph or other diagram. A typical rule could be: all points 3cm from the point (2,5). This would be a circle. Or all points that are the same distance ("equidistant") from the points (1,3) and (5,4). This would be the straight line perpendicular to and bisecting the line between the points.
Software/Applets used on this page

This page uses JSXGraph
JSXGraph is a cross-browser library for interactive geometry, function plotting, charting, and data visualization in a web browser. It is implemented completely in JavaScript, does not rely on any other library. It uses SVG and VML and is fully HTML5 compliant.
JSXGraph is a cross-browser library for interactive geometry, function plotting, charting, and data visualization in a web browser. It is implemented completely in JavaScript, does not rely on any other library. It uses SVG and VML and is fully HTML5 compliant.
Glossary
circle
a conic curve with equation (x-a)²+(y-b)²=r²
edge
the line connecting two vertices of a graph, also known as arc or line.
function
A rule that connects one value in one set with one and only one value in another set.
graph
A diagram showing a relationship between two variables.
The diagram shows a vertical y axis and a horizontal x axis.
The diagram shows a vertical y axis and a horizontal x axis.
locus
A set of points that fit a given rule.
perpendicular
one line being at right angles to another.
rule
A method for connecting one value with another.
straight
The type of line produced by a linear equation.
This question appears in the following syllabi:
Syllabus | Module | Section | Topic | Exam Year |
---|---|---|---|---|
AQA GCSE (9-1) Foundation (UK) | G: Properties and Constructions | G2: Problem Solving with Ruler and Compass | Loci | - |
CIE IGCSE (9-1) Maths (0626 UK) | 3 Geometry | C3.8 Problem Solving with Loci | Loci | - |
Edexcel GCSE (9-1) Foundation (UK) | G: Properties and Constructions | G2: Problem Solving with Ruler and Compass | Loci | - |
GCSE Foundation (UK) | Geometry | Construction | Loci | - |
OCR GCSE (9-1) Foundation (UK) | 8: Basic Geometry | 8.02d: Loci | Loci | - |
Universal (all site questions) | C | Construction | Loci | - |