Chapter 6 Basic Geometric Constructions 181
3. Lay off Side AE in a similar manner.
Continue until the required regular
pentagon is formed, Figure 6-29C.
Using the Polygon Command
(CAD Procedure)
1. Side length AB is given. Refer to
Figure 6-29A.
2. Enter the
Polygon
command and specify
the number of sides as five. fi
3. Enter the
Edge
option and select an endpoint.
Then, enter the given side length. If you
move the cursor, the pentagon is drawn
dynamically in a counterclockwise direction.
You can enter coordinates to specify the
length and direction of the edge, or you can
use Ortho mode and direct distance entry.
4. When you specify the endpoint of the
fi rst edge, the pentagon is generated fi
automatically. Refer to Figure 6-29C.
Figure 6-28. Constructing a square using the Polygon command. A—The diagonal length (Line AC) is given. B—The
Inscribed option is entered to specify a radial distance for an inscribed square. C—The completed square.
Center point
selected
A B C
Point selected
to specify
radius of circle
(one-half Line AC)
Figure 6-29. Constructing a regular pentagon from a given side length using a protractor.
A B
A
A
108–
B
B
A B
C C E
D
C
108– 108–
108– 108–
108–
Construct a
Regular
Pentagon with the Side
Length Given
CAD
Using a Protractor
(Manual Procedure)
A pentagon is a polygon with five sides. fi
A regular pentagon has five equal sides and fi
five equal interior angles. Each of the interior fi fi
angles measures 108°.
1. The length of Side AB is given,
Figure 6-29A.
2. With a protractor, lay off Side BC equal in
length to Side AB and at an angle of 108°.
The center of the angle should be at Point B,
Figure 6-29B.