Four congruent rectangles are placed in a hat-shaped configuration. What’s the angle between the lines connecting the opposite corners?
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The blockhat
Author: Rik D. Tangerman
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The corner pocket
A snooker player wants to corner a ball starting from a point on one side and bouncing two times from the opposite sides. Given the dimensions of the table in the figure, what’s the length of the track the snooker ball travels?
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The snowman mansion
A square and a half square are stacked in order to form a house-shaped quadrilateral. Inside two circles are closely packed. What’s the angle between the tangency points?
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Balancing balls
Two touching circles are placed on top of a right triangle. What’s the angle between the chords connecting the tangency points?
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The marble box
Two marbles of sizes π and 4π are enclosed in a rectangular box. What is the total area of the box?
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The folded sheet
A rectangular sheet of paper is folded in such a way that two equal angles are formed as shown. What fraction of the resulting quadrilateral is shaded?
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Moon over mountains
A rectangular frame encloses two congruent equilateral triangles and a unit circle. What is difference between width and height of the rectangle?
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The triangle tango
An isosceles triangle is attached to another triangle with a 60-degree angle as shown. Their opposite vertices are connected by a line segment of length 2. What is the area of the quadrilateral?
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The Pentagon peaches
Five equally sized peaches are closely packed in a pentagon-shaped box. Their midpoints are the vertices of a smaller pentagon. What fraction is shaded?
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An Egyptian sunset
A semicircle touches a large equilateral triangle (area equals 9) at its apex and a smaller adjacent equilateral triangle (area equals 1) at its base as shown. What is the total red area?