Categories

## Running man

What is the area of the coloured figure? Can you determine the area without counting the number of squares in each different-coloured shape?

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## Baby steps

The edges of a cyclic quadrilateral extend to two intersections. O is the circle centre. The two diagonals intersect inside the circle. What is the angle α?

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## The party hat II

An equilateral triangle with a circular arc through its red centre and two vertices. If the yellow area equals the green one, what’s the angle α?

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## The lighthouse

A parallelogram and four equilateral triangles. What is yellow : green?

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## Holes in my heart

The heart is divided into right triangles, each of which contains a blue circle. What is the total circumference of the blue circles in relation to the green perimeter and the lengths of the purple and orange lines in the centre?

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## Tip of the veil

A square with two right angles. What fraction is yellow?

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## The crosshairs

A regular pentagon and two semicircles. Prove that they are orthogonal, i.e. the tangents in the intersection point are orthogonal.

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## Carapace

Some chords and segments inside a semicircle. What is the ratio of red to blue?

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