An ellipse with its focal points, major and minor axis. What is x, the distance from the centre to the right focal point?
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Egg of Columbus
Author: Rik D. Tangerman
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The Roman katapult
Two quarter circles and a circle with a tangent line segment. What is pink : green?
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Angle chase
Two triangles are placed as shown. What is the angle α?
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Ice cream cone III
A triangle with its incircle and a cevian. What is red : yellow?
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In and out II
A couloured triangle and rectangle with extended sides and two circles. Prove that the triangle and the rectangle have equal areas.
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A mild temperature
Two squares and a diagonal. What’s the angle α?
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Side touches
Four triangles in a rectangle. The three red triangles have equal areas. What is blue : red?
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Slip sliding
Two squares share a vertex. The shown vertex can lie anywhere on the lower side. What is the maximum of red/blue?
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Centre of attraction III
Three congruent squares and an equilateral triangle. What is blue : orange?
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Compartments
An equilateral triangle with a cevian and two inscribed circles. What is yellow : red?