Texas Instruments TI-89, TI-92

106 Chapter 6: Basic Function Graphing

06BASFUN.DOC TI-89/TI-92 Plus: Basic Function Graphing (English) Susan Gullord Revised: 02/23/01 4:09 PM Printed: 02/23/01 4:18 PM Page 106 of 22

Steps

TI-89

Keystrokes

›

TI-92 Plus

Keystrokes Display

1. Display the

MODE dialog box.

For Graph mode, select

FUNCTION.

2. Display the Home screen. Then

store the radius, 5, in variable r.

5§jR

¥"

5§R

5!r

3. Display and clear the Y= Editor.

Then define y1(x) = rñ- xñ, the

top half of a circle.

In function graphing, you must define

separate functions for the top and

bottom halves of a circle.

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jRZ2|X

Z2d¸

¥#

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RZ2|X

Z2d¸

4. Define

y2(x) = ë rñ- xñ, the

function for the bottom half of

the circle.

The bottom half is the negative of the

top half, so you can define y2(x) =

ëy1(x).

·Y1cXd

5. Select the

ZoomStd

viewing

window, which automatically

graphs the functions.

In the standard viewing window, both

the x and y axes range from ë10 to

10. However, this range is spread

over a longer distance along the x

axis than the y axis. Therefore, the

circle appears as an ellipse.

„6„6

6. Select

ZoomSqr.

ZoomSqr increases the range along

the x axis so that circles and squares

are shown in correct proportion.

„5„5

Note: There is a gap between the top and bottom halves of the circle because each half is a

separate function. The mathematical endpoints of each half are (-5,0) and (5,0). Depending on

the viewing window, however, the plotted endpoints for each half may be slightly different from

their mathematical endpoints.

Preview of Basic Function Graphing

Graph a circle of radius 5, centered on the origin of the coordinate system. View the circle

using the standard viewing window (ZoomStd). Then use ZoomSqr to adjust the viewing

window.

Notice slight gap

between top and

bottom halves.

Use the full function name

y1(x), not simply y1.