Core Connections Integrated II, 2015
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Core Connections Integrated II, 2015 View details
3. Section 9.3
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Exercise 101 Page 519

Practice makes perfect
a The ratio of the areas A and B is the square of the linear scale factor between A and B.
(Linear scale factor)^2=(2/5)^2
(Linear scale factor)^2=2^2/5^2
(Linear scale factor)^2=4/25
The ratio of the areas of A and B is 425.
b The ratio of the perimeters of A and B is another way of expressing the linear scale factor.

The perimeter of A and B is 14:1 [0.4em] ⇕ Linear scale factor=14/1

Like in Part A, to find the ratio of the areas we have to square the linear scale factor.
(Linear scale factor)^2=(14/1)^2
(Linear scale factor)^2=14^2/1^2
(Linear scale factor)^2=196/1
The ratio of the areas of A and B is 196:1.
c As already discussed in Parts A and B, we know that the area of A is 81 times that of B. With this information, we can write the following equation.
Ratio of areas=81 ⇕ (Linear scale factor)^2=81 By solving for the linear scale factor we can determine the ratio of the perimeters.
(Linear scale factor)^2=81
Linear scale factor=± 9

(linear scale factor) > 0

Linear scale factor= 9
The linear scale factor is 9, which means the perimeter of A is 9 times greater than the perimeter of B.