A square containing a circle and two semicircles, all three having the same radius. What fraction is purple?
The Magdeburg hemispheres

A square containing a circle and two semicircles, all three having the same radius. What fraction is purple?
Five unit squares inside a larger square. What is the total area?
A tetrahedron with given vertex coordinates. What is its volume?
A semicircle containing a circle. One line segment is tangent to the circle and connects to the semicircle centre. The chord connects two tangency points. What fraction is blue?
Two large squares and three smaller ones of side length 5 are placed as shown. What is the pink area?
Two congruent rectangles are placed side by side. Two line segments form two coloured quadrilaterals and three triangles. What is the proportion purple : green?
Two equilateral triangles inside a square. What’s the proportion green : orange?
Two circles, four tangent line segments and a square. What’s the proportion red : blue?
Three rectangles and four triangles. Given that the red triangles have equal area, prove that the blue rectangles are similar.
Two diagonals of a circle are tangent to another circle. The chord passes through the tangency point. If the smaller circle has area 3, what is the area of the larger one?