## Basic Constructions

In geometry, constructions utilize only two tools – the straightedge (an unmarked ruler) and the compass.

### The Compass

Compasses come in a variety of styles. Become familiar with the compass you will be using before beginning your constructions.

**Suggestions for working with a compass:**

- Place several pieces of paper under your worksheet to allow the compass point to remain stable.
- Hold the compass lightly and allow the wrist to remain flexible.
- If you cannot manage to move your wrist when drawing circles, try rotating the paper under the compass.

### The Straightedge

A straightedge is generally a clear plastic tool devoid of markings. It most often appears in the shape of a triangle. A portion of a straightedge is visible in the lower left corner of the picture on the left below.

If you do not have a straightedge, a ruler may be used. Just remember to completely ignore the markings on the ruler.

### Basic Geometrical Constructions:

The basic constructions used in geometry include:

- copy a line segment
- copy an angle
- bisect a line segment
- bisect an angle
- construct perpendicular lines
- construct parallel lines
- construct isosceles triangle
- construct equilateral triangle

While the constructions listed above are considered the basic geometrical constructions, you should also be able to construct situations that require the use of these constructions.

**Constructing Angle Bisectors**

**Constructing Triangles**