A square sheet of paper is folded symmetrically from a corner. If the fold length is 4, what is the area of the triangle formed by the other three corners?
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The folded napkin
Tag: triangle
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Twin peaks
A rectangle with three line segments. What is the proportion yellow : red?
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Pyramidion
A triangle containing a semicircle and an equilateral triangle. What fraction is golden?
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Triple dice
An equilateral triangle with three congruent squares. What’s the angle α?
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Paper hat II
Two overlapping congruent right triangles. If |AB|=15 and |BC|=7, what is the total area?
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En garde
An isosceles triangle with two altitudes dividing each other in segments of length 4 and 5. What is the total triangle area?
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Distant peaks
Two isosceles triangles and a right angle. What is the proportion green : gold?
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The Lion King II
A regular hexagon and three squares. What is the proportion yellow : brown?
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The eye mask
A right triangle with its inscribed circle. Two cevians are drawn through the circle centre. What is the circle area in terms of triangle areas A and B?
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The red balloon
An equilateral triangle with an altitude. Two of its sides form the radii of the circular sector. What fraction of the area is covered by the red circle?