To find the radius of the original circle before dilation, you can divide the radius of the dilated circle by the scale factor.
Given:
- Scale factor = 15
- Radius of the dilated circle = 18 cm
The formula to find the original radius is:
\[ \text{Original radius} = \frac{\text{Dilated radius}}{\text{Scale factor}} \]
Now substituting the values:
\[ \text{Original radius} = \frac{18 , \text{cm}}{15} = 1.2 , \text{cm} \]
None of the provided responses match this answer, which indicates there may be a misunderstanding of the problem or discrepancy in the options provided.
If we were simply looking for the radius of the dilated circle multiplied by the scale factor (18 cm * 15), we'd get the radius of a hypothetically larger circle, but in this case, we’re confirming the calculation for the original radius.
So, based on the calculation, the radius of the original circle you dilated is 1.2 cm.