Categories
Beginner

Between the lines II

Two rectangles are at right angles and have equal area. Prove that the three black lines are parallel.

Categories
Beginner

A golden year

Two squares, a rectangle and a semicircle. What is yellow : green?

Categories
Beginner

Decorating the tree

A symmetric tree has decorative lines of equal slope, and of lengths 11 and 13. What is the area ratio of green to red to brown?

Categories
Beginner

The brick pile

Three congruent rectangles inscribed in a triangle. What fraction is brown?

Categories
Intermediate

Compartmentalization

A square with two circles and two common tangents. What’s red : blue?

Categories
Advanced

Through the roof

A semicircle with its centre. What is green : red in terms of the angles α and β?

Categories
Beginner

Lemon slice II

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

Categories
Advanced

Cuckoo in the nest

Two tangent semicircles inscribed in another semicircle. What is the total area?

Categories
Intermediate

Cozy in his chair

Orange and green semicircles with equally long but perpendicular diameters (both length 2) are partially covered by a blue canopy at angle α. What is the orange area, which is not covered by either of the other regions, in terms of α?

Categories
Intermediate

Stuck in the corner

A square with a diagonal and a right triangle. What fraction is red?