Two quarter circles and a red circle tangent to two chords. What fraction is red?
Tag: circle
The beam in your eye
Three parallelograms are inscribed in a circle. Prove that the common red vertex is the orthocentre of the dashed triangle.
The night sky
A semicircle containing two equilateral triangles and a circle. What’s the yellow fraction?
Entanglement
Two circles with two common tangents. Three red lines through tangency points and centres. Prove that they are concurrent.
The parachute
A circular sector is divided as shown. What fraction is red?
Polarisation
Two circles with three common tangents. Three tangency points are shown. Prove that they are collinear.
Move the earth
A square containing a semicircle, a tangent and a line segment from the tangency point. What fraction is green?
No pasaran
A semicircle with three tangents. The tangency points are shown. Prove that the red line segments are concurrent.
The orange fraction
A square containing a quarter circle and a red equilateral triangle. What’s the orange fraction?
The maxbox
A square containing a red square of variable size sharing a vertex with a blue rectangle. What is the maximal blue fraction?