Similar shapes

Two shapes are said to be similar if they are exactly the same shape, but are different in size.

Scaling all the lengths of the original shape can create a similar shape. This means they have been enlarged or shortened in the same proportions. We call this the scale factor.


Which of the following shapes are similar?

Eight shapes labelled A to H. A is a cube, B is a circle, C is an arrow, D is a rectangle, E is a rectangle, F is a cube, G is a circle, and H is an arrow

A and F are similar cubes: as the length, width and height are equal all cubes are similar.

B and G are similar circles: all circles are similar.

C and H are similar arrows: H is twice as big as C and has been rotated by 90°.

D and E are not similar: D has been stretched by scale factor 2 in one direction, but not the other.