Categories
Intermediate

Life is a dance

A quarter circle inside a square divides a line segment in parts of length 4 and 6. What is the square’s area?

Categories
Beginner

Colour confinement

A semicircle with three tangent line segments. What is its area in terms of lengths a and b?

Categories
Advanced

The earth projection

A circle touching a semicircle and a triangle. What is the proportion blue : green?

Categories
Beginner

Composition in red, blue and yellow

A rectangle containing red and blue squares and a yellow rectangle. What is the proportion red : (blue+yellow)?

Categories
Advanced

Cordon sanitaire

Two perpendicular lines and a third line. Four circles are tangent to all three lines. Prove that their areas satisfy AB=CD.

Categories
Intermediate

The green zone

A quarter circle and a right triangle inside a square. One of the vertices of the triangle is the square’s centre. What fraction of the square’s area is green?

Categories
Beginner

The kissing circles

A rectangle with three touching quarter circles. What fraction of its area is coloured?

Categories
Intermediate

The balancing act

A square with two perpendicular lines. What is the minimal blue fraction?

Categories
Intermediate

The commons

Two touching circles and a common tangent. Three triangles are formed by tangency points and centres. What is the area of the green triangle X in terms of areas A and B?

Categories
Intermediate

Softening the edges

A quarter circle contains a semicircle and a square. What fraction of the area is purple?