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## Primary colours

An equilateral triangle inside a rectangle. What is red : yellow : blue?

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An orange circle is squeezed inside a rectangle. Show that no matter how the blue point moves on the circle, the derived points Q and P will satisfy |QL| = |KP|.

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## Falling pillar II

Three congruent rectangles on a line. Prove that the four red points are cyclic.

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## The falling pillar

Three congruent rectangles on a line. What’s the angle α?

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## Night mountain

A rectangle containing three line segments. What fraction is blue?

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## Corner to corner

A rectangle inside a rectangle. What is the green area?

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## The ball pit

Two rectangles contain 6 congruent circles. The common rectangle side passes through the top centre. What’s yellow : red?

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A quarter circle of radius 1, a rectangle touching the circle in an arbitrary point and a yellow quadrilateral. What is the minimal perimeter of this quadrilateral?

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## The small cog

Two circles, a rectangle and two line segments. Prove that the red points are collinear.

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## The personal letter

Two rectangles share two vertices. What’s the green fraction?