Which face?
Which faces are opposite each other when this net is folded into a cube?
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-net.png?itok=JXjWyoXb)
It is placed on a table with the face
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-face%252520smaller.png?itok=m6YMicBP)
Which face is at the bottom?
This problem is taken from the World Mathematics Championships
Folding up the net
Imagine folding the net into a cube, starting with the face
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-face%252520smaller.png?itok=m6YMicBP)
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-folding%2525201.png?itok=_6m_BhJ7)
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-folding%2525202.png?itok=oBYgJdC-)
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-folding%2525203.png?itok=at_yKIU4)
So the face
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-answer.png?itok=ELTUqahM)
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-face%252520smaller.png?itok=m6YMicBP)
Considering edges
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-edges%252520explanation%252520better.png?itok=TCcMx6le)
Imagine the top and the base of a cube. The top shares a (green) edge with each side that isn't the base. The base shares a (blue) edge with each of these sides. These sides only share one edge with each other.
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-edges%252520net.png?itok=ghgph9rN)
Some of the green and blue edges are shown on the net to the right. It is enough to see that when the face
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-face%252520smaller.png?itok=m6YMicBP)
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![Which face? Which face?](/sites/default/files/styles/large/public/thumbnails/content-id-13670-answer.png?itok=ELTUqahM)