Question

к какой части речи относятся слова - уместившемся, сидевшая, изображенная?

Answer 1

Часть речи  причастие

Answer 2

Part of Speech of the Given Words

The words "уместившемся," "сидевшая," and "изображенная" belong to the part of speech called "причастие" (participle) in Russian grammar.

According to the search results, the words in question are participle forms, which are used to form complex predicate constructions and express the features of an action or state.