A square with four quarter circles of which the intersection points are the vertices of a yellow quadrilateral. What fraction of the total area is yellow?
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Square eyes
Category: Beginner
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The outsider
A circle with an inscribed regular pentagon, a square and a triangle. Prove that the point lies on the circumference of the circle.
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The life net
The vertices of a regular hexagon are connected to midpoints of opposing sides. What fraction is red?
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Below the line
Two squares share a vertex at the origin and have their sides along the x- and y-axis. Two vertices lie on the line satisfying x+2y=c. What is the proportion purple : yellow?
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The pivot table
Two squares share a vertex. What is the proportion purple : green?
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Colour confinement
A semicircle with three tangent line segments. What is its area in terms of lengths a and b?
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Composition in red, blue and yellow
A rectangle containing red and blue squares and a yellow rectangle. What is the proportion red : (blue+yellow)?
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The dark lord
Two congruent equilateral triangles and two squares. What’s the angle α?
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The open book
Three squares share four vertices. What is the proportion of the line segment lengths a and b?
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The kissing circles
A rectangle with three touching quarter circles. What fraction of its area is coloured?