Categories
Intermediate

The ball pool

A square having side length 12 contains a quarter, semi and full circle. The centres of the latter two are connected to the square’s centre to form a green triangle. What is it’s area?

Categories
Beginner

Square eyes

A square with four quarter circles of which the intersection points are the vertices of a yellow quadrilateral. What fraction of the total area is yellow?

Categories
Advanced

The Queen’s chamber

A right triangle with three squares forming a smaller inner triangle. What is the maximal blue fraction?

Categories
Beginner

The outsider

A circle with an inscribed regular pentagon, a square and a triangle. Prove that the point lies on the circumference of the circle.

Categories
Intermediate

Black hole sun

A square containing two quarter circles and a common tangent. What is the proportion yellow : black?

Categories
Intermediate

My two cents

A right triangle is divided in two triangles, one of which is isosceles. The two inscribed circles are congruent. What is the total area?

Categories
Beginner

The life net

The vertices of a regular hexagon are connected to midpoints of opposing sides. What fraction is red?

Categories
Intermediate

The lunar twins

Three circles are tangent to each other. The black chords go through their tangency points. Prove that the red chord is a diameter of the largest circle.

Categories
Beginner

Below the line

Two squares share a vertex at the origin and have their sides along the x- and y-axis. Two vertices lie on the line satisfying x+2y=c. What is the proportion purple : yellow?

Categories
Advanced

The red planet

A semicircle with a chord and a line segment perpendicular to it. What is the total area in terms of lengths a and b?