A semicircle with two tangents and a perpendicular line segment from a tangency point. What is the blue area in terms of lengths a and b?
Author: Rik D. Tangerman
The oppressed minority
A square with two inscribed squares. What is the maximal proportion green : blue?
Ceteris paribus
Three circles with their centres and a triangle ABC. Given that D is the midpoint of BC, prove that quadrilateral ABEF and triangle ECF have both equal perimeter and equal area.
Easing it down
Three squares share three vertices. What’s the angle α?
The pendulum
Two equilateral triangles share a side midpoint. What is the angle α?
The misfit
A rectangle is inscribed in a regular hexagon, covering 14/27 of its area. What is red : yellow : green?
In orbit
The smaller circle has its centre on the larger circle and is also the triangle’s incircle. Prove that the circle centres and the triangle vertex are collinear.
La Sagrada Familia
Two congruent right triangles on a common baseline have an overlap of variable size. What is the proportion of the minimal area to the maximal area?
The road less traveled
What is the area of the trapezium in terms of lengths a and b?
Cherry picking
Two quarter circles and a red circle tangent to two chords. What fraction is red?