Chapter 4: Parametric Graphing
94
Defining and Editing Parametric Equations
To define or edit a parametric equation, follow the steps in Chapter 3 for defining a function or
editing a function. The independent variable in a parametric equation is T. In parametric graphing
mode, you can enter the parametric variable T in either of two ways.
•
Press
„
.
•
Press
ƒ
[
T
].
Two components, X and Y, define a single parametric equation. You must define both of them.
Selecting and Deselecting Parametric Equations
The TI-84 Plus graphs only the selected parametric equations. In the Y= editor, a parametric
equation is selected when the
=
signs of both the X and Y components are highlighted. You may
select any or all of the equations
X1T
and
Y1T
through
X6T
and
Y6T
.
To change the selection status, move the cursor onto the
=
sign of either the X or Y component
and press
Í
. The status of both the X and Y components is changed.
Setting Window Variables
To display the window variable values, press
p
. These variables define the viewing window.
The values below are defaults for parametric graphing in Radian angle mode.
Note:
To ensure that sufficient points are plotted, you may want to change the
T
window variables.
Setting the Graph Format
To display the current graph format settings, press
y .
. Chapter 3 describes the format
settings in detail. The other graphing modes share these format settings; Seq graphing mode has
an additional axes format setting.
Tmin=0
Smallest T value to evaluate
Tmax=6.2831853
...
Largest T value to evaluate (2
p
)
Tstep=.1308996
...
T value increment (
pà
24)
Xmin=
L
10
Smallest X value to be displayed
Xmax=10
Largest X value to be displayed
Xscl=1
Spacing between the X tick marks
Ymin=
L
10
Smallest Y value to be displayed
Ymax=10
Largest Y value to be displayed
Yscl=1
Spacing between the Y tick marks