Problem 3 · 2022 Math Kangaroo
Easy
Spatial & Visual Reasoning
path-tracingreflection
The two-sided mirrors reflect the laser beam as shown in the small picture on the left. At which letter does the laser beam leave the picture on the right?
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Answer: B — B
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Hint 1 of 2
Each diagonal mirror turns the beam by a right angle; the small example shows which way.
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Hint 2 of 2
Step the beam square by square, bouncing 90 degrees at every mirror, until it reaches an edge.
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Approach: trace the beam, reflecting 90 degrees at each mirror
- Use the small picture to learn how each slanted mirror deflects the beam.
- Starting from the entry arrow on the big grid, advance the beam and turn it a quarter-turn at every mirror it hits.
- Following the bounces, the beam leaves the grid at letter B.
Mark:
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