Rooks on a chessboard

[Peter Mulder]

Assume there are 33 rooks arbitrarily placed on a chessboard. Why is it always possible to find a group of 5 rooks that can not attack eachother ?

 

[BigBeachBanana]

Prove that if 33 rooks are placed on a chessboard, at least five don't attack one another

The question asks to prove that when 33 rooks are placed on an $8 \times 8$ chessboard that there are a total of 5 rooks that aren't attacking each other. What I know: 64 squares Rooks attack in

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