Chapter 6 Basic Geometric Constructions 205
Connect Two
Parallel
Lines with Reversing Arcs
of Unequal Radii with One
Radius Given
CAD
Using a Compass
(Manual Procedure)
1. Two parallel lines (Lines AB and CD)
and Radius R
1
are given, Figure 6-56A.
2. Draw Line BC, Figure 6-56B.
3. Draw a line perpendicular to Line AB at
Point B. Lay off Radius R
1
on this line.
The endpoint becomes Point E. With
Point E as the center, use a compass to
strike Arc R
1
from Point B to the intersec-
tion with Line BC. This intersection is
Point F, Figure 6-56C.
4. Draw a line perpendicular to Line CD at
Point C. Extend Line EF to intersect this
perpendicular. This intersection is Point G.
5. Using Point G as the center and the
distance from Point G to Point C as the
radius, draw Arc GC from Point C to
Point F. This arc and the first arc drawn fi
form the required arcs. These arcs are
tangent to each other and to the given
parallel lines.
Using the Start, End, Radius
Option (CAD Procedure)
1. Two parallel lines (Lines AB and CD)
and Radius R
1
are given. Refer to
Figure 6-56A.
2. Draw a line perpendicular to Line AB
at Point B. Refer to Figure 6-56C. Lay
off Radius R
1
on this line. The endpoint
becomes Point E. Draw a line perpen-
dicular to Line BE at the same length.
The endpoint becomes Point F.
3. Enter the
Arc
command. Select Point B as
the start point.
4. Enter the
End
option. Select Point F as the
endpoint.
5. Enter the
Radius
option and enter the
given radius value. This draws the first fi
arc (Arc R
1
).
6. To draw the second arc (Arc GC), enter
the
Arc
command and enter the
Continue
option. Specify the endpoint as Point C.
The two arcs are tangent to each other
and to the given parallel lines.
Figure 6-56. Connecting two parallel lines with reversing arcs of unequal radii when one radius is given.
A B
R1
R1
A B
C D
A B
C D
C
A
B
E
F
G
C
D