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The boot

Two squares and some line segments. Find the relation between the angles α and β.

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Four squares

How does the average of the areas of the blue and green squares compare with the area of the purple square?

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Steam roller

Two intersecting circles. Express the lengths b and the common tangent d in terms of c (the distance between the centres) and the angles β and γ.

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Fair scoop

What is the ratio of areas purple : orange if the cone angle is 45°, and the circular arc is a semicircle?

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Square offspring

Three squares and two line segments. What’s the angle α?

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Triangle offspring

Four equilateral triangles. Prove that the three black line segments are concurrent.

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The punctured hexagon

A regular hexagon, a square and an equilateral triangle. Show that the top vertex of the triangle is on the hexagon circumcircle.

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Two-story A-frame house

The slanted lines are perpendicular, and the one in the bottom story bisects the angle. Show that red equals green, so the stories have the same height.

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Angle versus height

What is the ratio orange/green?

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The Bedouin tent

A semicircle and a triangle of which one side is tangent to the semicircle. What is the angle α?