Respuesta :

CastleRook
This is the concept of transformations, given that ABC was rotated it implies that it retained it's original dimensions. This means that ABC is proportional to EFD. Therefore, given that EF=4.2 cm, DF=3.6 cm and DE=4.5 cm. The CB=FD=3.6 cm
the answer is 3.6 i got it correct on my test :)