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.

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

Example Input: Sentence: 'two baseball players look on awaiting the pitch to be made'. Reverse all words of length '5' in the given sentence.
Example Output: two baseball players look on awaiting the hctip to be made

Example Input: Sentence: 'a small dog standing on top of a fire hydrant'. Reverse all words of length '3' in the given sentence.
Example Output:
a small god standing on pot of a fire hydrant