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1.1.3 Proof by contradiction (A-level only)

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Question 50

A design engineer is specifying the dimensions of a rectangular metal brace for a heavy-duty storage rack. The width of the brace is W W\,W cm and the height is H H\,H cm, where W,H∈Z+W, H \in \mathbb{Z}^+W,H∈Z+. The diagonal length of the brace is D D\,D cm.

a.

Provide a specific example of values for WWW, HHH, and D D\,D such that all three lengths are even integers.

[1]
b.

By using proof by contradiction, show that it is impossible for W W\,W and H H\,H to both be odd integers if D D\,D is an integer.

[5]

1.1.3 Proof by contradiction (A-level only) Questions

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