*Macmillan Science Library: Mathematics*. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.

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## Basic Tools

**Straightedge.** A straightedge is a geometric tool used to construct straight lines. It contains no marks. As the name says, it is a "straight edge." A ruler can be used as a straightedge by simply ignoring the measuring marks on it.

**Ruler.** A ruler is a geometric tool used to measure the length of a line segment. A ruler is basically a straightedge with marks usually used for measuring either inches or centimeters. To use a ruler, place the zero mark on the point to begin the measurement. To stop measuring, look at the mark on the ruler that lies over the point at which the measurement is to end.

**Compass.** A compass is a V-shaped tool used to construct circles or arcs of circles. (See sketch below on left.) One side of the "V" holds a pencil and the other side is a point...

This section contains 949 words(approx. 4 pages at 300 words per page) |