Enlargements and scale factors

There are 22 NRICH Mathematical resources connected to Enlargements and scale factors
L-triominoes
problem

L-triominoes

Age
14 to 16
Challenge level
filled star filled star empty star
L triominoes can fit together to make larger versions of themselves. Is every size possible to make in this way?
Golden Triangle
problem

Golden triangle

Age
16 to 18
Challenge level
filled star filled star empty star
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.