TI-84 Plus and TI-84 Plus Silver Edition Guidebook

12. Press r to obtain numerical results and answer the questions at the beginning of this section.

Tracing begins at

Tmin

on the first parametric equation (

X1T

and

Y1T

). As you press

~ to trace the curve, the cursor follows the path of the ball over time. The values for

X

(distance),

Y

(height), and

T

(time) are displayed at the bottom of the screen.

Defining and Displaying Parametric Graphs

TI-84 Plus Graphing Mode Similarities

The steps for defining a parametric graph are similar to the steps for defining a function graph.

Chapter 4 assumes that you are familiar with Chapter 3: Function Graphing. Chapter 4 details aspects of parametric graphing that differ from function graphing.

Setting Parametric Graphing Mode

To display the mode screen, press z. To graph parametric equations, you must select parametric graphing mode before you enter window variables and before you enter the components of parametric equations.

Displaying the Parametric Y= Editor

After selecting parametric graphing mode, press o to display the parametric Y= editor.

In this editor, you can display and enter both the X and Y components of up to six equations,

X1T

and

Y1T

through

X6T

and

Y6T

. Each is defined in terms of the independent variable

T

. A common application of parametric graphs is graphing equations over time.

Selecting a Graph Style

The icons to the left of

X1T

through

X6T

represent the graph style of each parametric equation. The default in parametric mode is

ç (line), which connects plotted points. Line, è (thick), ë (path),

ì (animate), and í (dot) styles are available for parametric graphing.

Chapter 4: Parametric Graphing 92

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.

Tmin=0

Tmax=6.2831853

...

Tstep=.1308996

...

Xmin=

L10

Xmax=10

Xscl=1

Ymin=

L10

Ymax=10

Yscl=1

Smallest T value to evaluate

Largest T value to evaluate (2 p

)

T value increment ( pà

24)

Smallest X value to be displayed

Largest X value to be displayed

Spacing between the X tick marks

Smallest Y value to be displayed

Largest Y value to be displayed

Spacing between the Y tick marks

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.

Chapter 4: Parametric Graphing 93