An equilateral triangle with two perpendiculars to a point that is at the same height as the triangle centre. What is red : yellow?
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Centre of attraction
Tag: length
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The Pythagoras bug
Two blue squares and two red right triangles. What are the proportions of the triangle sides?
Author: Matthew Arcus.
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The skew bridge
Two points are on opposite sides of a channel. A skew bridge, which has a fixed direction (for instance North East), can be placed anywhere along the channel. Where to place it such that the path from A to B over the bridge is the shortest?
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The film projector
A square and two congruent circles with three common tangents. What’s yellow : red?
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The dug-in heel
A rectangle containing a right triangle. What’s red : blue?
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The quarter trampoline
A quarter circle with two chords of given length. What is the area of the orange quadrilateral?
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The sunny side
An equilateral triangle inside a rectangle. What’s red : yellow : blue?
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The maternal bond
Three tangent semicircles and a circle. One tangency point is shown. Prove that red : green = yellow : blue.
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Hang a right
Two circles, one having its centre on the other, and four line segments. Prove that the three coloured line segments are congruent.
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Methane
Four orange unit circles and their red centres. What is the radius of the green circle? Kindly provided by Marshall W. Buck.