In this task, you need to reverse all words of a given length in the sentence. The number of letters in a word determine its length. For example, the length of the word "apple" is 5.

Sentence: 'a triangular grouping of jet planes flying in the sky'. Reverse all words of length '3' in the given sentence.
a triangular grouping of tej planes flying in eht yks

Sentence: 'decorative street signs on a post in front of trees'. Reverse all words of length '10' in the given sentence.
evitaroced street signs on a post in front of trees

Sentence: 'a man and a little boy on skis on a ski hill'. Reverse all words of length '2' in the given sentence.

a man and a little boy no skis no a ski hill