2011

Table Of Contents
Subtract Areas from Combined Areas
You can subtract more than one area from a combined area as you calculate.
For example, if you have calculated the area of a floor plan, you can subtract
the area of a room.
Example: Subtraction of Areas from a Calculation
In the following example, the closed polyline represents a metal plate with
two large holes. The area of the polyline is first calculated and then the area
of each hole is subtracted. The area and perimeter or circumference of each
object displays, with a running total after each step.
The Command prompt sequence is
Command: area
Specify first corner point or [Object/Add/Subtract]: a
Specify first corner point or [Object/Subtract]: o
(ADD mode) Select objects: Select the polyline (1)
Area = 0.34, Perimeter = 2.71
Total area = 0.34
(ADD mode) Select objects: Press Enter
Specify first corner point or [Object/Subtract]: s
Specify first corner point or [Object/Add]: o
(SUBTRACT mode) Select objects: Select the lower circle (2)
Area = 0.02, Circumference = 0.46
Total area = 0.32
(SUBTRACT mode) Select objects: Select the upper circle (3)
Area = 0.02, Circumference = 0.46
Total area = 0.30
(SUBTRACT mode) Select circle or polyline: Press Enter
Specify first corner point or [Object/Add]: Press Enter
You can also use REGION to convert the plate and the holes to regions, subtract
the holes, and then use the Properties palette or the LIST command to find
the area of the plate.
TIP Use the QuickCalc calculator to convert from one system of area units to
another. For more information, see
Use the QuickCalc Calculator on page 627.
624 | Chapter 17 Use Precision Tools