Four squares and five shared vertices. If the orange area is 4, what is the green area?
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The dangling square
Month: August 2021
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The yellow sailboat
A square, two equilateral triangles and an extended side. What is the proportion yellow : blue?
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Mondriaan II
A square contains three squares (black sides), one of which has an extended side (blue). What is the proportion yellow : blue?
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Warning triangle II
A square, a triangle and two equal angles. What is the angle α?
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The green quad
Three semicircles and a circle all touching each other. The diameters of the two smallest semicircles are given. The large triangle connects three tangency points. What is the area of the green quadrilateral?
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The strawberry ice cream
Two tangent circles and a triangle. The figure has reflection symmetry in the vertical diameter d, of which one ninth is above the horizontal chord. What fraction is pink?
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Seventies tipi II
A triangle containing two tangent semicircles. What’s the proportion α : β?
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The inner sanctum
A square with four congruent equilateral triangles. What fraction is yellow?
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The colour purple
A rectangle is split by two perpendicular lines. The four circles pass through vertices and intersection points. Their centres form a purple quadrilateral. What fraction of the large rectangle area does it cover?
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Triangle quartet II
Three coloured equilateral triangles share three vertices. Prove that the triangle formed by their centres is also equilateral.1This puzzle is also known as Napoleon’s Theorem.