Questions & Answers about Официант был очень вежливый.
Why is вежливый in the nominative case here? Doesn't the verb был require the instrumental case (вежливым)?
With the past tense of "to be" (был, была, etc.), adjectives can take either the nominative or the instrumental case. The nominative (вежливый) is very common in everyday speech and often implies a permanent trait. The instrumental (вежливым) is slightly more formal and often suggests a temporary state (like being polite specifically during that one meal). Both are perfectly correct here!
Can I use the short-form adjective вежлив instead of вежливый in this sentence?
Yes, you can say Официант был очень вежлив. Because the adjective is acting as the predicate (describing the subject rather than directly modifying a noun), the short form works perfectly. Just note that вежлив sounds a bit more formal or literary, while the long form вежливый is what you will hear most often in casual conversation.
How would this sentence change if the server were a woman?
You would use the feminine noun официантка, and both the verb and the adjective must change to match her feminine gender. The sentence becomes: Официантка была очень вежливая (or вежливой if you choose to use the instrumental case).