Can you work out the area of the inner square and give an explanation of how you did it?
Follow the instructions and you can take a rectangle, cut it into 4 pieces, discard two small triangles, put together the remaining two pieces and end up with a rectangle the same size. Try it!
Two circles are enclosed by a rectangle 12 units by x units.
The distance between the centres of the two circles is x/3 units.
How big is x?