# UNIT 01: GEOMETRIC CONSTRUCTIONS

Here you can see a video created by KhanAcademy to revise basic ideas in geometry and how we represent them with symbols.

## Language and Notation of Basic Geometry

• POINT (A, B, C,…)

A point is an exact position or location on a plane surface. It is important to understand that a point is not a thing, but a place. A point has no size.

• LINE (r, s, t, p…)

It is a point in movement or it is the union between two points. Line hasn’t got a beginning or an end.

• RAY (r, s, t, p…)

The ray has got beginning but not end.

•  SEGMENT (AB, BC;…)

It is a part of the line. It has a beginning and an end. We can measure the lenght of segments.

The Ruler-and-compass construction is the construction of lengths, angles, and other geometric figures using only an idealized ruler and compass. These constructions are very important to be able to draw complex drawings.

## Locus

Locus: In Geometry a locus (plural: loci) is a set of points whose location satisfies or is determined by one or more specified conditions.

1. Every point satisfies a given condition.
2. Every point satisfying that condition is in that particular locus.

Examples: circle, line bisector, angle bisector…