This is the so called predicative expression (predikativo). It often represents a result of an action or is the complement of an opinion or idea (like with kredi). The adjective says something about either the subject or the object (both being in the nominative case). Here are some examples (and note how the English sentences have the same structure).
- I deem him nice. = Mi opinias lin afabla.
- We elected her president. = Ni elektis ŝin prezidento.
- I arrived home tired. = Mi alvenis hejme laca.
- We painted the house blue. = Ni farbis la domon blua.
- Don't call me an idiot. = Ne nomu min idioto.
If you use the same construction applied to an infinitive or a subordinate clause, then the predicative expression should be an adverb (like usual when you say something like “Helpi homojn estas grave”).
- I find helping people important. = Mi opinias helpi homojn grave.
The word order is not too important; you can swap it around a bit, but make sure that the predicative expression does not become a normal adjective/adverb, as that would change the meaning of the sentence:
- La malsana knabino vekiĝis. ≠ La knabino vekiĝis malsana.
In the first sentence the girl was already sick and just woke up. In the second sentence, the girl was perfectly fine when she went to bed, but woke up sick.
Sometimes it can be ambiguous whether the predicative expression applies to the subject or the object:
- I drove the guy home drunk. = Mi hejmenveturigis la viron ebria.
This could either mean that I, the driver, was drunk, or that I drove the guy home and when we arrived he was still drunk. Here you might be tempted wonder why we then not just put the predicative in the accusative case. That changes the meaning of the sentence, because it becomes an adjective:
- Mi hejmenveturigis la viron ebrian. = I drove the drunk guy home.