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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. 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.

### 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.

Full Glossary List

## This question appears in the following syllabi:

SyllabusModuleSectionTopicExam Year
AQA GCSE (9-1) Foundation (UK)G: Properties and ConstructionsG2: Problem Solving with Ruler and CompassLoci-
CIE IGCSE (9-1) Maths (0626 UK)3 GeometryC3.8 Problem Solving with LociLoci-
Edexcel GCSE (9-1) Foundation (UK)G: Properties and ConstructionsG2: Problem Solving with Ruler and CompassLoci-
GCSE Foundation (UK)GeometryConstructionLoci-
OCR GCSE (9-1) Foundation (UK)8: Basic Geometry8.02d: LociLoci-
Universal (all site questions)CConstructionLoci-