I didn't really get the connection between the airport security staff and the visual angle mathematics? How does knowledge of the equations of the visual angle assist security staff in any way? After the opening paragraph there was no further mention of airport security or how this maths was of use in practical applications.

I normally enjoy Plus articles very much, but unless I missing something obvious (in which case apologies!), this one doesn't quite follow through on its premise.

This question is for testing whether you are a human visitor and to prevent automated spam submissions.