1
general::
Act the part of in public, usually alluding to a performance on stage. For example, She got wonderful reviews when she appeared as Portia. This idiom uses appear in the sense of "to come before the public," a usage dating from the late 1500s.
American Heritage Idioms
2
general::
Phrase(s): appear as something
1. to act a certain part in a play, opera, etc. • Madame Smith-Franklin appeared as Carmen at the City Opera last season. • The actor refused to appear as a villain in the play. 2. [for something] to be seen or occur in a particular form or with particular characteristics. • The tumors appear as shadows on the X-ray. • The first signs of the disease appear as a fever and a rash.
McGrawhill's American Idioms And Phrasal Verbs