Evaluate Polar Expressions on the TI-83 Plus

You can use the TI-83 Plus graphing calculator to evaluate polar expressions that you have entered and graphed. To evaluate polar equations at a specified value of

follow these steps:

1. Graph the equation in a viewing window that contains the specified value of

   

   To get a viewing window containing the specified value of

   

   that value must be between

   

   and

   

2. Set the Format menu to ExprOn and CoordOn.

3. Press [2nd][TRACE] to access the Calculate menu.

4. Press [1] to select the value option.

5. Enter the specified value of

   

   To do so, use the keypad to enter the value of

   

   If you make a mistake when entering your number, press [CLEAR] and re-enter the number.

6. Press [ENTER].

   After you press [ENTER], the first highlighted polar equation in the Y= editor appears at the top of the screen, the cursor appears on the graph of that equation at the specified value of

   

   and the coordinates of the cursor appear at the bottom of the screen.

7. Repeatedly press

   

   to see the value of the other graphed polar equations at your specified value of

   

   Each time you press

   

   the name of the polar equation being evaluated appears at the top of the screen and the coordinates of the cursor location appear at the bottom of the screen.

   

If you’re planning to evaluate polar equations at several specified values of

consider constructing a user-defined table.