Graphics Reference
In-Depth Information
b
b
a
a
b
a
Fig. 10.1.
Examples of adjacent/supplementary, opposite and complementary angles.
c
a
a
c
d
b
b
d
Fig. 10.2.
1st intercept theorem.
10.1.1 Angles
By definition, 360
◦
or 2
π
[radians] measure one revolution. The reader should
be familiar with both units of measurement, and how to convert from one to
the other (see page 26). Figure 10.1 shows examples of
adjacent/supplementary
angles (sum to 180
◦
)
opposite
angles (equal), and
complementary
angles (sum
to 90
◦
).
10.1.2 Intercept Theorems
Figures 10.2 and 10.3 show scenarios involving intersecting lines and parallel
lines that give rise to the following observations:
•
First intercept theorem:
a
+
b
a
=
c
+
d
c
b
a
=
d
,
(10.1)
c
•
Second intercept theorem:
a
b
c
d
=
(10.2)
