Hide and Delete Objects in Cabri Jr.

You can hide and delete objects in the Cabri Jr. geometry application for the TI-84 Plus graphing calculator. There is a big difference between hiding and deleting an object. If you hide an object, you can, if you so choose, bring it back into view at a later time. But if you delete an object, it is gone for good.

How to hide an object in Cabri Jr.

The first picture provides an example of when you may want to hide an object. Because Cabri Jr. has no tool that instantly creates a tangent to a circle, the tangents in this picture were created by first constructing radii, and then by constructing lines perpendicular to these radii.

If all you really want to see is the circle and tangents, you can hide the radii. If you were to delete the radii, the tangents would also be deleted because they were constructed perpendicular to the radii and are thus dependent on the existence of the radii.

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To hide an object, follow these steps:

  1. Press [GRAPH][1] to select the Hide/Show tool from the F5 menu.

    A picture of the Hide/Show tool appears in the upper-left corner of the screen.

  2. Use the arrow keys to move the cursor to the object you want to hide.

    The object blinks and the cursor changes to an eraser, as illustrated in the second picture, where the radius is to be hidden.

  3. Press [ENTER] to hide the object.

    The object appears as a dotted object and the cursor changes to a pen, as illustrated in the third picture.

  4. Move the cursor away from the object.

    The object vanishes, and the cursor changes to a solid arrow.

After hiding one object, the Hide/Show tool remains active (as indicated by the picture in the upper left of the screen) until you deactivate it. So if you want to hide more objects, just repeat Steps 2 through 4. When you are finished using the tool, you deactivate it by pressing [CLEAR] or by selecting another menu item.

How to redisplay hidden objects in Cabri Jr.

To redisplay hidden objects, press [GRAPH][1] to select the Hide/Show tool from the F5 menu. Use the arrow keys to move the cursor to the location of the hidden object. When the cursor reaches the object, that object is displayed as a dotted object and the cursor changes to a pen, as illustrated in the third picture.

Press [ENTER] to show the object. The object blinks and the cursor changes to an eraser. Move the cursor away from the object. The object is redisplayed and the cursor changes to a solid arrow.

Because the Hide/Show tool remains active until you deactivate it, you can continue to hide and show other objects. When you are finished using this tool, deactivate it by pressing [CLEAR] or by selecting another menu item.

How to delete objects in Cabri Jr.

If you delete an object, then all other objects whose construction is dependent on the deleted object will also be deleted. For example, the tangents in the first picture were constructed perpendicular to the radii of the circle. If you were to delete the radii, the tangents would also vanish because their existence is dependent on the existence of the radii.

To delete an object, press [CLEAR] to ensure that no tools are active. Use the arrow keys to move the cursor to the object. When the object starts blinking, press [DEL] to delete the object. If you regret deleting that object, press [Y=][2] to undo what you just did.

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