If the radius of circle O is 14 meters and it is dilated by a scale factor of 2.5, then what will be the circumference of circle O′ ?(1 point)

Responses

44 m
44 m

220 m
220 m

10 m
10 m

345 m
345 m

1 answer

To find the circumference of circle O' after dilation, we first need to calculate the circumference of the original circle O and then apply the scale factor.

The formula for the circumference \( C \) of a circle is given by:

\[ C = 2 \pi r \]

where \( r \) is the radius of the circle.

  1. Calculate the original circumference of circle O:

    • The radius \( r \) is 14 meters. \[ C = 2 \pi (14) = 28\pi , \text{meters} \]
  2. Determine the new radius after dilation:

    • The scale factor for dilation is 2.5. \[ r' = 2.5 \times 14 = 35 , \text{meters} \]
  3. Calculate the circumference of the dilated circle O′: \[ C' = 2 \pi (35) = 70\pi , \text{meters} \]

  4. Approximate \( \pi \) as 3.14 for numerical calculation: \[ C' \approx 70 \times 3.14 = 219.8 , \text{meters} \]

If we round it off for the answer choices given, we see that the closest response to 219.8 m is:

220 m