"The mirror has a large frame."
Translation:Le miroir a un large cadre.
I would also like to know why 'grand' is not acceptable in this case. I have read all the comments and have clicked the links and I still do not know.
"Gros" is a matter of volume, whereas the French "large" means wide or broad.
I hope that everyone will upvote this question because Sitesurf's explanation is an important part of French logic that everyone needs to know.
If I'm interpreting your question right (about why the adjective goes before the noun here), it's because adjectives describing an object's size go before the noun. It's an exception to the general rule, along with several other categories (beauty, age, goodness, number, size).
I put "Le miroir a un cadre large" and was marked correct. Not really sure why. Why didn't I get dinged for having the adjective in the wrong place?