176 Section 2 Drafting Techniques and Skills
Using the Line and Trim
Commands (CAD Procedure)
1. Angles A and B and the included side
length are given, Figure 6-22A.
2. Enter the
Line
command and draw a base
line the length of Side AB, Figure 6-22B.
Enter coordinates to specify the length
and direction or use Ortho mode and
direct distance entry.
3. Enter the
Line
command and draw
Angles A and B at the opposite ends of
Line AB. Draw Angle A at 30°. Draw
Angle B at 135°. This angle is calculated
for polar coordinate entry by measuring
in a counterclockwise direction from 0°
horizontal. It can also be determined by
calculating the supplement of Angle B
(180° – 45° = 135°). Draw the inclined
lines for Angles A and B using polar
coordinates or polar tracking and direct
distance entry. Also, draw the lines long
enough so that they extend past where
they intersect.
4. Enter the
Trim
command and trim
the two lines to the point where they
intersect. Refer to Figure 6-22B. You can
select each line as a cutting edge and
trim the lines separately or trim the lines
to the intersection. Triangle ABC is the
required triangle, Figure 6-22C.
Figure 6-22. Using the Line and Trim commands to construct a triangle from two angles and the included side
length. A—Side AB is given. B—Inclined lines for Angles A and B are drawn. The lines are extended past where
they intersect and then trimmed to the intersection. C—Triangle ABC after trimming the line segments.
A B
B
A
30
–
45
–
30
–
45
–
B A A B
A B C
Line segments
to trim
Lines drawn
past
intersection
C
Construct an
Equilateral
Triangle
CAD
Using a Triangle or Compass
(Manual Procedure)
An equilateral triangle has three equal
sides and three equal angles (three 60° angles).
This type of triangle can be drawn with a
30°-60° triangle or a compass.
1. Side length AB is given, Figure 6-23A.
2. Draw a base line and lay off Side AB,
Figure 6-23B.
3. There are two different ways of completing
the triangle. The method using two angles
and the included side length, described
previously, can be used with a 30°-60° tri-
angle, Figure 6-23C. The method using
three given side lengths with a compass
can also be used, Figure 6-23D. With
either method, the resulting triangle
(Triangle ABC) is an equilateral triangle.
Using the Polygon Command
(CAD Procedure)
You can construct an equilateral triangle
using the
Line
command and coordinates for the
length of the base and the sides, but a quicker
method is to use the
Polygon
command. This
command is used to create regular polygons with
three or more sides. After entering the command,
the number of sides is specified. The command fi fi