A rectangle with given side lengths is folded back and forth such that the corner touches the opposite side as shown. What is the minimal shaded fraction?
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The sneak peek
Tag: area
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The glass ceiling
Three squares, two of which share a vertex. What is the total area?
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Three folds
A square divided by three line segments. What’s the proportion yellow : purple?
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Égalité
A square with its diagonal and a circle. If red is equal to blue, what’s the angle α?
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Spiegel im Spiegel
A triangle with an inscribed triangle. What fraction of the former does the latter cover in terms of lengths a, b, c, d, e and f?
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The green necktie
A square with several line segments. What fraction is green?
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House of Orange
A right triangle with a red and yellow square attached. Two circular arcs centered in the triangle vertices. What is the area of the orange rectangle in terms of red and yellow?
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Out of proportion
An equilateral triangle containing a parallelogram, another equilateral triangle and a circular arc that is tangent in its base vertices. What is the proportion pink : blue?
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Head above water
A unit square with an extended side immersed in another square. What is the area of the red triangle?
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The framing effect
Four squares, three of which are coloured. What’s the area of the blue one?