Problem 5 · 2023 Math Kangaroo
Easy
Spatial & Visual Reasoning
reflectionfolding
Kristina has a piece of see-through foil on which some points and lines are drawn. She folds the foil along the dotted line. What can she see now?
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Answer: C
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Hint 1 of 2
The foil is see-through, so folding lays the marks on one half exactly on top of the marks on the other half.
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Hint 2 of 2
Mirror the marks on the moving half across the dotted line, then read off which picture the combined marks make.
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Approach: reflect one half across the fold line and overlay the marks
- Because the foil is transparent, folding places the marks of the moving half directly onto the fixed half.
- Mirror each point and line on the moving half across the dotted fold line to find where it lands.
- Combining the original marks with their mirror images gives the picture in option C.
- So the answer is C.
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