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(1) A circle with an area of 
8pi square centimeters is dilated so that its image has an area of 
32 pi square centimeters. What is the scale factor of the dilation?
A 2
B 4
C 8
D 16

(11) A circle with an area of 8π 8 \pi square centimeters is dilated so that its image has an area of 32π 32 \pi square centimeters. What is the scale factor of the dilation?\newlineA 22\newlineB 44\newlineC 88\newlineD 1616

Full solution

Q. (11) A circle with an area of 8π 8 \pi square centimeters is dilated so that its image has an area of 32π 32 \pi square centimeters. What is the scale factor of the dilation?\newlineA 22\newlineB 44\newlineC 88\newlineD 1616
  1. Given Information: Original area of the circle is 8π8\pi square centimeters. New area of the circle is 32π32\pi square centimeters. The area of a circle is proportional to the square of its radius.
  2. Define Scale Factor: Let's call the scale factor 'kk'. The new area is k2k^2 times the original area because when a figure is dilated, the area is multiplied by the square of the scale factor.
  3. Set Up Equation: Set up the equation: k2×original area=new areak^2 \times \text{original area} = \text{new area}. So, k2×8π=32πk^2 \times 8\pi = 32\pi.
  4. Solve for k2k^2: Divide both sides by 8π8\pi to solve for k2k^2: k2=32π8πk^2 = \frac{32\pi}{8\pi}.
  5. Final Scale Factor: Simplify the equation: k2=4k^2 = 4.
  6. Final Scale Factor: Simplify the equation: k2=4k^2 = 4. Take the square root of both sides to solve for kk: k=2k = 2 or k=2k = -2. Since a scale factor cannot be negative, k=2k = 2.

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