Texas Instruments PLUS TI-89 - Manual (Page 123)

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
³
TI - 89
Keystrokes
›
TI - 92 Plus
Keystrokes Display
1. Display the MODE dialog box.
For Graph mode, select
FUNCTION .
3
B 1
¸ 3
B 1
¸
2. Display the Home screen. Then
store the radius, 5, in variable r .
"
5 § j R
¸ ¥ "
5 § R
¸ 5! r
3. Display and clear the Y= Editor.
Then define y1(x) = r ñ - x ñ , the
top half of a circle.
In function graphing, you must define
separate functions for the top and
bottom halves of a circle.
¥ #
ƒ 8 ¸
¸ 2 ]
j R Z 2 | X
Z 2 d ¸ ¥ #
ƒ 8 ¸
¸ 2 ]
R Z 2 | X
Z 2 d ¸
4. Define y2(x) = ë r ñ - x ñ , 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) =
ë y1(x).
¸
· Y 1 c X d
¸ ¸
· Y 1 c X d
¸
5. Select the ZoomStd viewing
window, which automatically
graphs the functions.
In the standard viewing window, both
the x and y axes range from
ë 10 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.