Graphics Reference
In-Depth Information
c
c
a
a
b
b
Fig. 10.10.
The Theorem of Pythagoras states that
c
2
=
a
2
+
b
2
.
10.1.12 Trapezoid
Figure 10.11 shows a
trapezoid
which has one pair of parallel sides
h
apart.
The mid-line
m
and area are given by
m
=
1
2
(
a
+
b
)
A
=
mh
(10.13)
10.1.13 Parallelogram
Figure 10.12 shows a
parallelogram
. This is formed from two pairs of inter-
secting parallel lines, so it has equal opposite sides and equal opposite angles.
The altitude and diagonal lengths are given by
h
=
b
·
sin
α
(10.14)
d
1
,
2
=
a
2
+
b
2
2
a
b
2
h
2
±
−
(10.15)
and the area by
A
=
ah
(10.16)
10.1.14 Rhombus
Figure 10.13 shows a
rhombus
, which is a parallelogram with four sides of
equal length
a
. The area is given by
A
=
a
2
sin(
α
)=
d
1
d
2
2
(10.17)
