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?

Categories
Advanced

The Magdeburg hemispheres

A square containing a circle and two semicircles, all three having the same radius. What fraction is purple?

Categories
Intermediate

The sleeping bag

A semicircle containing a circle. One line segment is tangent to the circle and connects to the semicircle centre. The chord connects two tangency points. What fraction is blue?

Categories
Intermediate

The bishop’s hat

Two overlapping regular pentagons share two vertices. What fraction is the overlap area?

Categories
Beginner

The leaning tower

A trapezium with it’s diagonals. Two areas are given. What faction is coloured?