III. Working With A Graph
B. MATH
8. ISECT (intersection)
This will locate points of intersection of two graphs. If you have more than two functions graphed, it is better to turn off (select) all of the functions except the two you will be working with.
Example: Find the points of intersection of the functions shown.
Enter.

Use ZDECM
and graph. 
Go to ISECT.

You will see
this screen. 
Move the
cursor and press . 
Just press
again. 
Ignore Guess?
and press again. 
This is the
intersection. 