I'm not sure about how to do it with the filter, but using the search box you can do the following:
for questions that have answers posted (even if none are accepted)
this will return results that have at least 1 answer. You can change the number to find questions that have more answers too if you wish.
for questions that have an accepted answer
This will find questions that have an accepted answer (so therefore at least one answer). Note that this one gives the accepted answer as the search result, not the question, but clicking on it will take you to the full Q&A.
When you start typing into the search box at the top of the screen you will see it offers search tips that help refine your search results.
A bit of a deeper look at the advanced search options reveals also
This will return Questions that have an accepted answer. You can also combine these with the other advanced search options.
If you click on "Advanced Search Tips" when you've made your search you'll be given a list of all of these
Search type Search syntax
Exact "words here"
Score score:3 (3+)
Answers answers:3 (3+)
And a link to How do I search?