Categories
Intermediate

Pyramidion

A triangle containing a semicircle and an equilateral triangle. What fraction is golden?

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Advanced

The ocean sunset

A semicircle is inscribed in a rectangle. What is the minimal covered fraction?

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Advanced

The satellite

A circle containing three squares. What fraction is coloured?

Categories
Beginner

The blue pill

A regular octagon containing a blue hexagon. All line segments have equal length. What fraction is blue?

Categories
Intermediate

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?

Categories
Intermediate

The strawberry ice cream

Two tangent circles and a triangle. The figure has reflection symmetry in the vertical diameter d, of which one ninth is above the horizontal chord. What fraction is pink?

Categories
Beginner

The inner sanctum

A square with four congruent equilateral triangles. What fraction is yellow?

Categories
Intermediate

The colour purple

A rectangle is split by two perpendicular lines. The four circles pass through vertices and intersection points. Their centres form a purple quadrilateral. What fraction of the large rectangle area does it cover?

Categories
Intermediate

Marble box II

Two squares, three circles and a common tangent. What fraction is coloured?

Categories
Advanced

The lemon slice

A semicircle is inscribed in a quarter circle. What is the minimal yellow fraction?