Categories
Intermediate

House of Orange

A right triangle with a red and yellow square attached. Two circular arcs centered in the triangle vertices. What is the area of the orange rectangle in terms of red and yellow?

Categories
Advanced

Out of proportion

An equilateral triangle containing a parallelogram, another equilateral triangle and a circular arc that is tangent in its base vertices. What is the proportion pink : blue?

Categories
Intermediate

Head above water

A unit square with an extended side immersed in another square. What is the area of the red triangle?

Categories
Intermediate

The framing effect

Four squares, three of which are coloured. What’s the area of the blue one?

Categories
Beginner

Projection bias

Two regular pentagons are placed side by side. What’s the proportion blue : green?

Categories
Intermediate

Take five origami

Divide a rectangular piece of paper in five pieces of equal area. You only have a pair of scissors at your disposal, but you are allowed to make straight folds to guide you.

Categories
Beginner

The voting pencil

A square and a rectangle share a vertex. Two triangle areas are given. What is the total area?

Categories
Intermediate

The red triangle

A square containing an isosceles triangle with given side lengths. What fraction is red?

Categories
Beginner

Confined enclosure

A square containing four smaller squares. What fraction of its area is orange?

Categories
Intermediate

Check and balance

A square divided by three line segments. The red and blue areas are equal. What’s the length proportion a : b?