Locus #1

In the figure below, the "slider" controls the distance from point A to point B. Try moving the slider. What happens to point B?

Try moving point B around the screen. What happens to AB?

Set your slider so that AB = 5 (or as close as you can get it). This means that point B is 5 units away from point A. Move point B to a different location without adjusting the slider. The new location of B is also 5 units away from point A. Right-click on point B and turn the trace on. This will show all the places that B goes when you move it. Without adjusting the slider, move point B around the screen. Notice that it always stays 5 units away from point A. The trace of B shows the locus of points that are 5 units from A. What does this locus look like? Be specific. Use appropriate vocabulary.

How would the locus change if we changed AB to 10?