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Taping tarps brainteaser

David Shaw

29 May, 2019

Gerri has two identical square tarpaulins. Unfortunately, these tarps aren’t quite big enough to cover the brand new spa bath.

So Gerri’s decided to cut the tarps and tape them together to make a bigger tarp.

They want their final tarp to be a square, and they want it to be as big as possible.

Can you work out a way to make a big square without wasting any of the tarp material? What’s the fewest number of cuts they need to make?

Scroll down for the answer!

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Brainteaser answer

If Gerri cuts each tarp in half diagonally, they can arrange them with the original corner angles in the middle and the diagonals around the outside to make one big square. And it only takes two cuts!

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Categories:

Brainteaser, Maths

Tags:

mathematical sciences, number, problem solving, squares

3 responses

Martin

29 May, 2019

Depends on what one considers “a cut” – Gerri could place one tarp on top of the other and cut both at the same time; would this be considered a single cut?

An alternative is to cut one tarp from corner to opposite corner and then do another cut from an uncut corner to its opposite corner. Then sew the uncut side of a triangle to an unsewn edge of the uncut tarp — repeat that for each triangle. The results would be a square that is the same size as in the solution given above.

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David

29 May, 2019

Good points!
I like your second solution – it’s probably better in the real world. There’s an uncut tarp in the middle, so it’ll provide good protection even if the tape leaks. And if the tape fails, you’ll only lose a corner whereas in our solution, the whole thing would fall to pieces.

Plus, when you’re finished, you still have an uncut tarp to use for other things.

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Malik

31 May, 2019

You really make me scratch my brain
Excellent puzzle but so simple solution

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