If you use a scale factor of 1/5

Question

to create a circle with radius 18 cm, what is the radius of the original circle you dilated?(1 point)
Responses

180 cm
180 cm

9 m
9 m

3.6 cm
3.6 cm

90 cm

Answer 1

To find the radius of the original circle before applying the scale factor, you can use the formula:

\[ \text{radius of original circle} = \text{radius after dilation} \div \text{scale factor} \]

Here, the scale factor is \( \frac{1}{5} \) and the radius after dilation is \( 18 \) cm.

Now, calculate the radius of the original circle:

\[ \text{radius of original circle} = 18 , \text{cm} \div \frac{1}{5} = 18 , \text{cm} \times 5 = 90 , \text{cm} \]

Thus, the radius of the original circle is 90 cm.