Chapter 9: Split Screen
137
Chapter 9:
Split Screen
Getting Started: Exploring the Unit Circle
Getting Started is a fast-paced introduction. Read the chapter for details.
Use
G-T
(graph-table) split-screen mode to explore the unit circle and its relationship to the
numeric values for the commonly used trigonometric angles of 0
¡
30
¡
, 45
¡
, 60
¡
, 90
¡
, and so on.
1. Press
z
to display the mode screen. Press
†
† ~ Í
to select
Degree
mode. Press
† ~
Í
to select
Par
(parametric) graphing mode.
Press
† † † † ~ ~ Í
to select
G-T
(graph-
table) split-screen mode.
2. Press
† † † † ~ Í
to display the format
screen. Press
† † † † † ~ Í
to select
ExprOff
.
3. Press
o
to display the Y= editor for
Par
graphing
mode. Press
™ „ ¤ Í
to store
cos(T)
to
X1T
. Press
÷ ˜ „ ¤ Í
to store
sin(T)
to
Y1T
.
4. Press
p
to display the window editor. Enter
these values for the window variables.
Tmin=0 Xmin=
L
2.3 Ymin=
L
2.5
Tmax=360 Xmax=2.3 Ymax=2.5
Tstep=15 Xscl=1 Yscl=1
5. Press
r
. On the left, the unit circle is graphed
parametrically in
Degree
mode and the trace
cursor is activated. When
T=0
(from the graph
trace coordinates), you can see from the table on
the right that the value of
X1T
(
cos(T)
) is
1
and
Y1T
(
sin(T)
) is 0. Press
~
to move the cursor to the
next 15
¡
angle increment. As you trace around the
circle in steps of 15
¡
, an approximation of the
standard value for each angle is highlighted in the
table.
6. Press
y -
and change
Indpnt
to
Ask
.
