Categories
Advanced

The birdwatcher

Two congruent circles and a right triangle inside a semicircle. What fraction is blue?

Categories
Intermediate

The tin foil hat

A circle inside a quarter circle. The triangle connects the two tangency points and the top of the quarter circle. What’s the angle α?

Categories
Intermediate

The fez

A circle and a semicircle inside a square. What’s the length proportion of the two chords?

Categories
Intermediate

The cleaver

Four squares, a rectangle and a circle. What is the proportion brown : grey?

Categories
Beginner

The partial eclipse

Two circles and a radius connecting their centres. What is the length of the parallel chord?

Categories
Beginner

Papillon

Four quarter circles of radius 1, each containing a square. What is the blue area?

Categories
Beginner

The pillbox

Three touching circles in a rectangle and a common tangent. What’s the angle?

Categories
Beginner

The headphones

A unit square, a semicircle, a right triangle and an isosceles triangle. What is the total purple area?

Categories
Intermediate

The Eye of Horus

A semicircle containing two equilateral triangles containing a circle. What fraction is blue?

Categories
Beginner

The winged messenger

A semicircle and two quarter circles pass through the same point. What’s the angle α?