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Beginner

The hammock

A square inscribed in a triangle. Two areas are given. What is the square’s area?

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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 partial eclipse

Two circles and a radius connecting their centres. What is the length of the parallel chord?

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Papillon

Four quarter circles of radius 1, each containing a square. What is the blue area?

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The pillbox

Three touching circles in a rectangle and a common tangent. What’s the angle?

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The headphones

A unit square, a semicircle, a right triangle and an isosceles triangle. What is the total purple area?

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En bloc

Two similar rectangles. If the small one has area 4 what is the area of the large rectangle?

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The winged messenger

A semicircle and two quarter circles pass through the same point. What’s the angle α?

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The skyscraper

A blue parallelogram with an extended diagonal. What is the proportion green : orange?

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Beginner

The seventies tipi

An isosceles triangle with two inscribed congruent semicircles. What is the angle α?