Start with an acute triangle and form a new triangle from the points of tangency of its inscribed circle. Continue this process to make make the triangle with blue vertices. What is the maximum possible angle at a blue vertex?
A unit square and a rectangle. What is the blue area?
Points B, C, D are on a circle with centre O and diameter COC’. Point E is on the line BC such that DE is perpendicular to COC’. Show that the perpendicular bisectors of EB and ED and the line DC’ are concurrent.
Two circles and four coloured common tangents. Prove they are congruent.
A rectangle is divided into six rectangles of equal area. What fraction is green?
Three squares on a grid. What is the ratio of the areas red : green : purple?