Getting Started: Graphing A Circle - Texas Instruments TI-80 Manual Book

Getting Started: Graphing a Circle

Getting Started is a fast-paced introduction. Read the chapter for details.
Graph a circle of radius 10, centered on the origin in the standard viewing
window. To graph a circle, you must enter separate formulas for the upper and
lower portions of the circle. Then use ZSQUARE to adjust the display to make
the functions appear as a circle.
Make sure that your TI-80 is in
are turned off.
STAT PLOTS
1. Press ( to display the
c | @ a d ¸ to enter the expression
100
2
Y1=‡(100–X )
circle.
The bottom half of the circle is defined by
2
Y2=‡(100–X )
one function in terms of another; so to define
, press · 2 G (to display the
Y2=LY1
variables menu)
2. Press *
6
way to reset the Window variables to the standard
values. It also graphs the functions; you do not need
to press ,.
Notice that the functions appear as an ellipse in
the standard viewing window.
3. To adjust the display so each "dot" represents an
equal width and height, press *, and then
select
ZSQUARE
now appear as a circle on the display.
4. To see the ZSQUARE
) and notice the values for
and YMAX .
5. If you want to see the graph again, press ,.
4-2 Function Graphing
FUNC
edit screen. Press 2 ]
Y=
, which defines the top half of the
. However, you can also define
1 (to select Y1 ).
to select ZSTANDARD
. The functions are replotted and
Window variables, press
mode and all
Y=
. This is a quick
to
5
XMIN , XMAX , YMIN ,