AutoCAD® 2009 & AutoCAD LT® 2009 Bible

Chapter 7. Drawing Curves and Points

AutoCAD and AutoCAD LT offer a number of ways to create curved objects. You can draw circles, arcs, ellipses, and donuts (also spelled as doughnuts). In this chapter, I also cover point objects, which are neither curves nor lines but don't deserve their own chapter.

Note

Several complex objects—such as polylines, splines, regions, and boundaries—involve curves. These are covered in Chapter 16.

Drawing Circles

Circles are common objects in drawings. In mechanical drawings, they often represent holes or wheels. In architectural drawings, they may be used for doorknobs, trash baskets, or trees. In electrical and piping schematics, they are used for various kinds of symbols.

Understanding the circle options

Table 7.1. Six Ways to Draw a Circle

Option	Description
Center, Radius	This option is the default. Specify the center and then the radius. You can type the radius as a distance, or pick a point where you want the circumference to be.
Center, Diameter	Specify the center. Choose the Diameter option and type the length of the diameter, or pick a point to specify the diameter.
2P (2 Points)	Choose the 2p option. Specify one point on the circumference, and then an opposite point on the circumference. These two points define the diameter of the circle.
3P (3 Points)	Choose the 3p option. Specify three points on the circumference.
Tan, tan, radius (Tangent, Tangent, Radius) ...