Two congruent circles and a right triangle inside a semicircle. What fraction is blue?
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The birdwatcher
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The tin foil hat
A circle inside a quarter circle. The triangle connects the two tangency points and the top of the quarter circle. What’s the angle α?
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The hammock
A square inscribed in a triangle. Two areas are given. What is the square’s area?
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Lazy Friday
Four congruent squares plus another one. What is the angle α?
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The fez
A circle and a semicircle inside a square. What’s the length proportion of the two chords?
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The orange belt
Three squares and three shared vertices. Prove that the orange quadrilateral is in fact a parallelogram.
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The cleaver
Four squares, a rectangle and a circle. What is the proportion brown : grey?
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The green field
A square is divided in two quadrilaterals of given area. What fraction of the square’s perimeter is red?
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The twin triangles
Two squares share a vertex. Prove that the red triangle is congruent to the blue one.
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The partial eclipse
Two circles and a radius connecting their centres. What is the length of the parallel chord?