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Author: Rik D. Tangerman
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Stars on 45
A square containing a rectangle. What is the red fraction?
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Video: Pandora’s box II
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Staying in line
Three squares and a regular pentagon. Prove that the three red vertices are collinear.
Two squares and some line segments. Find the relation between the angles α and β.
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Video: What’s your angle?
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Video: Pentagon pleasure
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The belly button
A quarter circle with a right triangle. Prove that the red point is the incentre of this triangle.
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Video: Under the dome
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Pandora’s box II
Five squares and a diagonal. What fraction of the largest square is coloured?