Consider the given figures ABCD and A'B'C'D'.
The side AB is 4 units, while side A'B' is 2 units, so the scale factor is given by,
[tex]SF=\frac{A^{\prime}B^{\prime}}{AB^{}}=\frac{2}{4}=\frac{1}{2}[/tex]
Thus, the scale factor of the dilation is 1/2.
Note that the scale factor can be calculated by taking the ratio of any two corresponding sides i .e.
[tex]SF=\frac{A^{\prime}B^{\prime}}{AB}=\frac{B^{\prime}C^{\prime}}{BC}=\frac{C^{\prime}D^{\prime}}{CD}=\frac{A^{\prime}D^{\prime}}{AD}[/tex]
