How to Measure an Angle in Cabri Jr.
For Cabri Jr. on the TI84 Plus to recognize the existence of an angle, that angle must contain three defining points — the vertex and a point on each side of the angle. Also, Cabri Jr. recognizes a point only if it appears on the screen as a small square.
If the angle you want to measure does not contain the small squares representing these three defining points, then Cabri Jr. cannot measure it. After you have constructed the three points defining your angle, Cabri Jr. can find its measure.
Cabri Jr. measures all angles in degrees — even if the Mode is set to radian measure.
To find the degree measure of an already constructed angle containing three defining points, follow these steps:

Press [GRAPH] to select the Appearance menu. Use the
keys to place the cursor on the Measure option. Press
to display the Measure submenu. Use the
to place the cursor on the Angle option, and then press [ENTER] to select that option.
A symbol of the Angle tool appears in the upperleft corner of the screen.

Use the arrow keys to move the cursor to an existing point on one side of the angle and press [ENTER] to select that point.
Cabri Jr. uses a small square to indicate that a point exists.

Use the arrow keys to move the cursor to the vertex of the angle and press [ENTER] to select the vertex.
The vertex must always be the second point that defines the angle.

Use the arrow keys to move the cursor to an existing point on the other side of the angle and press [ENTER] to select that point.
The measure of the angle appears on the screen.

Use the arrow keys to relocate that measurement on the screen and press [ENTER] to anchor that location.

To find the measure of another angle, repeat Steps 2 through 5. When you are finished measuring angles, press [CLEAR] or select another menu item.