Texas Instruments PLUS TI-89 - Manual (Page 155)

138 Chapter 8: Polar Graphing
08POLAR.DOC TI-89/TI-92 Plus: Polar Graphing (English) Susan Gullord Revised: 02/23/01 10:57 AM Printed: 02/23/01 2:14 PM Page 138 of 6
As in function graphing, you can explore a graph by using the
following tools. Any displayed coordinates are shown in polar or
rectangular form as set in the graph format.
Tool For Polar Graphs:
Free-Moving
Cursor Works just as it does for function graphs.
„ Zoom Works just as it does for function graphs.
¦ Only x ( xmin , xmax , xscl ) and y ( ymin , ymax , yscl )
Window variables are affected.
¦ The q Window variables ( q min , q max , q step ) are not
affected unless you select 6:ZoomStd (which sets
q min = 0 , q max = 2 p , and q step = p /24 ).
… Trace Lets you move the cursor along a graph one q step at a
time.
¦ When you begin a trace, the cursor is on the first
selected equation at
q min .
¦ 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 polar graphs. These tools are
based on q values. For example:
¦ 1:Value displays an r value (or x and y , depending
on the graph format) for a specified q value.
¦ 6:Derivatives finds dy/dx or dr/d q at a point defined
for a specified q value.
Exploring a Graph
Tip: During a trace, you can
also evaluate r(
q ) by typing
the q value and pressing
¸ .
Tip: You can use
QuickCenter at any time
during a trace, even if the
cursor is still on the screen.