Texas Instruments PLUS TI-89 - Manual (Page 149)

132 Chapter 7: Parametric Graphing
07PARAM.DOC TI-89/TI-92 Plus: Parametric Graphing (English) Susan Gullord Revised: 02/23/01 10:56 AM Printed: 02/23/01 2:13 PM Page 132 of 6
As in function graphing, you can explore a graph by using the
following tools.
Tool For Parametric Graphs:
Free-Moving
Cursor Works just as it does for function graphs.
„ Zoom Works just as it does for function graphs, with the
following exceptions:
¦ Only x ( xmin , xmax , xscl ) and y ( ymin , ymax , yscl )
Window variables are affected.
¦ The t Window variables ( tmin , tmax , tstep ) are not
affected unless you select 6:ZoomStd (which sets
tmin = 0 , tmax = 2 p , and tstep = p /24 ).
… Trace Lets you move the cursor along a graph one tstep at a
time.
¦ When you begin a trace, the cursor is on the first
selected parametric equation at
tmin .
¦ QuickCenter applies to all directions. If you move
the cursor off the screen (top or bottom, left or
right), press ¸ to center the viewing window
on the cursor location.
¦ Automatic panning is not available. If you move the
cursor off the left or right side of the screen, the
TI -89 / TI-92 Plus will not automatically pan the
viewing window. However, you can use
QuickCenter .
‡ Math Only 1:Value , 6:Derivatives , 9:Distance , A:Tangent , and
B:Arc are available for parametric graphs. These tools
are based on t values. For example:
¦ 1:Value displays x and y values for a specified
t value.
¦ 6:Derivatives finds dy/dx , dy/dt , or dx/dt at a point
defined for a specified t value.
Exploring a Graph
Tip: During a trace, you can
also evaluate x(t) and y(t) by
typing the t value and
pressing
¸ .
Tip: You can use
QuickCenter at any time
during a trace, even if the
cursor is still on the screen.