problem Ford Circles Age 16 to 18 Challenge level Can you find the link between these beautiful circle patterns and Farey Sequences?
problem Bicentric Quadrilaterals Age 14 to 16 Challenge level Investigate the properties of quadrilaterals which can be drawn with a circle just touching each side and another circle just touching each vertex.
problem Curvy areas Age 14 to 16 Challenge level Have a go at creating these images based on circles. What do you notice about the areas of the different sections?
problem Partly Circles Age 14 to 16 Challenge level What is the same and what is different about these circle questions? What connections can you make?
problem Shaping Up Age 7 to 11 Challenge level Are all the possible combinations of two shapes included in this set of 27 cards? How do you know?
problem Overlapping Again Age 7 to 11 Challenge level What shape is the overlap when you slide one of these shapes half way across another? Can you picture it in your head? Use the interactivity to check your visualisation.
problem Angle to Chord Age 14 to 16 Challenge level Weekly Problem 23 - 2008 A triangle has been drawn inside this circle. Can you find the length of the chord it forms?
problem Oh so Circular Age 14 to 16 Challenge level The diagram shows two circles and four equal semi-circular arcs. The area of the inner shaded circle is 1. What is the area of the outer circle?