unexpected behavior of a variable (slider) becoming undefined
When I have multiple sliders to represent interacting variables, sometimes they take on an undefined state, causing graphical elements related to that variable to disappear.
For instance, in the attached geogebra file, there are 5 variables for angles, alpha, beta, gamma, delta and epsilon. The idea is that some of these variables depend on the other ones (imposing restrictions on their range and sometimes limiting it to a single value).
When I set the gamma variable to 45 degrees and I gradually increase the value of the beta variable, sometimes this causes the delta variable to become undefined (for many values of beta between 30 and 60 degrees and gamma at the upper limit of its range). Is there any way to prevent this from happening?
Here are two screenshots to illustrate the problem visually (one just before the problem occurs and one as the problem occurs):