文档介绍：MultiMedia CD
by Jack Zecher
An audioi/visual
presentation of the
tutorial exercises
SDC
PUBLICATIONS
Schroff Development Corporation
AutoCAD® 2002 Tutorial 2-1
Lesson 2
Geometric Construction Basics
♦ Create and Save AutoCAD drawing files.
♦ Use the AutoCAD visual reference
commands.
♦ Draw, using the LINE and CIRCLE
commands.
♦ Use the mand.
♦ Define Positions using the Basic Entry
methods.
♦ Use the AutoCAD Pan Realtime option.
2-2 AutoCAD® 2002 Tutorial
Introduction
Learning to use a CAD system is similar to learning a new language. We need to begin
with the basic alphabet and learn how to use it correctly and effectively through practice.
This will require learning some new concepts and skills as well as learning a different
vocabulary. All CAD systems create designs using basic geometric entities. Many of the
constructions used in technical designs are based upon two-dimensional planar geometry.
The method and number of operations that are required to plish the constructions
are different from one system to another.
In order to e effective in using a CAD system, we must learn to create geometric
entities quickly and accurately. In learning to use a CAD system, lines and circles are the
first two, and perhaps the most important two, geometric entities that we need to master
the skills of creating and modifying. Straight lines and circles are used in almost all
technical designs. In examining the different types of planar geometric entities, we can
see that triangles and polygons are planar figures bounded by straight lines. Ellipses and
Splines can be constructed by connecting arcs with different radii. As we gain some
experience in creating lines and circles, similar procedures can be applied to create other
geometric entities. In this lesson, we will examine th