The rectangles are 3 by 4. Which of the three bounding octagons have similar shape?
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Three octagons
Tag: rectangle
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Fan of cards
N coloured rectangular cards are arranged with a common vertex and common angle α between cards. If a single card has perimeter P, what is the perimeter of the coloured region, in terms of N, P, and α?
Extra condition: N and α are such that at least two edges of the bottom card are visible.
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Distant sea
A rectangle with three line segments. What fraction is blue?
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Bullet train
What is the ratio of orange and green areas? (The orange triangle is 45-45-90)
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Folding magic
One corner of a rectangular piece of paper is folded as shown. Prove that the red line segments are concurrent.
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Primary colours
An equilateral triangle inside a rectangle. What is red : yellow : blue?
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The basketball court
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?