It is possible (I discovered!) to filter out unanswered questions from a search.
It doesn't seem to be possible to do the same when you pull up questions by clicking on a tag.
The question search URL uses a query string to which the 'answered' condition can be added with a '&'. The tag URL is static. (That exhausts the HTML expertise I can bring to bear on the problem!)
If my analysis is correct, is there a way of adding an answered filter to tag 'searches'?