Construct Points of Intersection in Cabri Jr.
The Cabri Jr. geometry application for the TI84 Plus calculator can construct the points of intersection of any pair of the following types of objects: lines, segments, circles, and sides of triangles/polygons. To construct points of intersection, follow these steps:

Select the Intersection tool from the Point submenu.
To do this, press [WINDOW]. Repeatedly press
to highlight the Point tool. Press
to display the point submenu. Use the
keys to highlight the Intersection tool, and press [ENTER] to select that tool. A picture of the tool appears in the upperleft corner of the screen and the cursor becomes a solid arrow.

Use the arrow keys to move the cursor to one of the objects in the intersecting pair of objects and press [ENTER].
When the object you are approaching starts blinking, press [ENTER] to select it. This is illustrated in the first picture, where one of the diagonal sides of the polygon is selected.

Use the arrow keys to move the cursor to the other object in the intersecting pair and press [ENTER].
The point or points of intersection appear on the screen and the Intersection tool remains active.
You can construct more points of intersections by repeating Steps 2 and 3. When you are finished using this tool, you deactivate it by pressing [CLEAR] or by selecting another menu item.