How is this polygon called? (the one over the circles)
square
rhomboid
concave square
concave rhomboid
In this Ehrenstein illusion the sides of a square placed inside a pattern of concentric circles take an apparent curved shape. But in reality, the sides are straight.
reach: rather globalgeometryillusionsmathematicsoptical illusionstechnology
Answers by country
square
rhomboid
concave square
concave rhomboid
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25
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27
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56
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36
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260
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