## 8.1 Outline

- Introduction
- measure
- precision/accuracy
- accuracy procedure used in this book
- metric world in 2010

- Measuring length
- define length
- U.S. system
- metric system

- standard length units
- U.S. system
- metric system; prefixes

- define length
- Perimeter
- define perimeter
- formulas
- equilateral triangle
- rectangle
- square

- Circumference
- terminology
- define circle; radius, diameter, center, semicircle
- define circumference

- the number pi

- terminology

## 8.1 Essential Ideas

To measure an object is to assign a number to its size.

The number representing is linear dimension, as measured from end to end, is called its measure or **length**.

To measure length, use the following units of measurement:

U.S. System | Metric System |

inch (in.) | meter (m) |

foot (ft; 12 in.) | centimeter (cm; 1/100m) |

yard (yd; 36 in.) | kilometer (km; 1,000 m) |

mi (mi) |

The perimeter of a polygon is the sum of the lengths of the sides of that polygon.

The **circumference **of a circle is the distance around the formula.