Texas Instruments TI-83 PLUS - Manual (Page 161)

TI-83 Plus Parametric Graphing 158
Defining and Displaying Parametric Graphs
TI-83 Plus Graphing Mode Similarities
The steps for defining a parametric graph are similar to the steps for
defining a function graph. Chapter 4 assumes that you are familiar with
Chapter 3: Function Graphing. Chapter 4 details aspects of parametric
graphing that differ from function graphing.
Setting Parametric Graphing Mode
To display the mode screen, press z . To graph parametric equations,
you must select Par graphing mode before you enter window variables
and before you enter the components of parametric equations.
Displaying the Parametric Y= Editor
After selecting Par graphing mode, press o to display the parametric Y=
editor.