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Two squares sharing a vertex and two overlapping coloured quadrilaterals from square side midpoints. What is the area proportion of the blue and the red quadrilateral?

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## Ends of the spectrum

Two squares and a rectangle. Prove that red = blue.

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## Touch the sides

What is the area of a green quadrilateral that fits inside a quarter circle, and has perpendicular diagonals?

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## Paranoid centroid

A square is divided in four triangles of which the red centroids are shown. What fraction is green?

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## Blocking the view

Two squares and one extended side. What is purple : red?

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## Nearly the same

Two rectangles are positioned with the side of each one along the diagonal on the other. Furthermore, two of their sides have the same length, as marked. What is the quotient of areas (A+B)/(C+D)?

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## The blue lagoon

Five congruent brown triangles inside a rectangle. What fraction is brown?

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## Similar but different

Four similar triangles make up a large triangle. Express red in terms of green and yellow.

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## Pushed together

A square containing two semicircles. The red line segment is a common tangent. What fraction is green?

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## Lifting the veil

A blue triangle and a red rectangle with an extended side. Prove they have equal area.