problem L-triominoes Age 14 to 16 Challenge level L triominoes can fit together to make larger versions of themselves. Is every size possible to make in this way?
problem Golden triangle Age 16 to 18 Challenge level Three triangles ABC, CBD and ABD (where D is a point on AC) are all isosceles. Find all the angles. Prove that the ratio of AB to BC is equal to the golden ratio.