Rotate Geometric Objects in Cabri Jr. on the TI-84 Plus - dummies

Rotate Geometric Objects in Cabri Jr. on the TI-84 Plus

By C. C. Edwards

You can rotate geometric objects in the Cabri Jr. application on the TI-84 Plus calculator. When a geometric object is rotated, it is rotated about a given point through a given angle. To rotate an already constructed geometric object, follow these steps:

  1. Construct the point of rotation and construct the three points that determine the angle of rotation.

    The point about which rotation occurs can be one of the points on the already constructed object. The first picture shows that the already constructed triangle is to be rotated about the point above the triangle.

    The angle through which it is to be rotated appears in the upper-right corner of the screen. Your angle does not have to have sides like the angle in this picture. All that is needed are three points.


  2. Press [GRAPH] to access the F4 Transformation menu. Use


    to move the cursor to the Rotation option and press [ENTER] to select that option.

    A symbol of the tool appears in the upper-left corner of the screen.

  3. Use the arrow keys to place the cursor on the object to be rotated and press [ENTER] to select that object.

    Cabri Jr. can rotate only one object at a time. The object to be rotated blinks when the cursor is placed on it. When selecting a triangle or quadrilateral, all sides of the object must be blinking to select the whole object instead of just one side of the object. To do this, place the cursor inside the object and move it slightly until all sides are blinking.

  4. Use the arrow keys to move the cursor to the center of rotation and press [ENTER].

  5. For each point defining the angle of rotation, use the arrow keys to move the cursor to that point, and then press [ENTER] to select the point. The vertex must be the second point selected.

    The rotation of the original object appears along with the original object.

  6. Repeat Steps 3 through 5 to rotate more objects. When you are finished rotating objects, press [CLEAR] or select another menu item.

After rotating objects, if you move the center or rotation or one of the points defining the angle of rotation, the rotated object moves to the location determined by the new center of rotation or by the new angle of rotation.

The Symmetry tool in the F4 Transformation menu can be used to rotate an object 180 degrees about a given point. This tool works just like the Rotation tool, except you don’t have to define the angle because this tool uses a 180 degree angle.