# Lesson 9

Applying Area of Circles

### Problem 1

A circle with a 12-inch diameter is folded in half and then folded in half again. What is the area of the resulting shape?

### Solution

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### Problem 2

Find the area of the shaded region. Express your answer in terms of \(\pi\).

### Solution

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### Problem 3

The face of a clock has a circumference of 63 in. What is the area of the face of the clock?

### Solution

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(From Unit 3, Lesson 8.)### Problem 4

Which of these pairs of quantities are proportional to each other? For the quantities that are proportional, what is the constant of proportionality?

- Radius and diameter of a circle
- Radius and circumference of a circle
- Radius and area of a circle
- Diameter and circumference of a circle
- Diameter and area of a circle

### Solution

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(From Unit 3, Lesson 7.)### Problem 5

Find the area of this shape in two different ways.

### Solution

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(From Unit 3, Lesson 6.)### Problem 6

Elena and Jada both read at a constant rate, but Elena reads more slowly. For every 4 pages that Elena can read, Jada can read 5.

- Complete the table.
pages read by Elena pages read by Jada 4 5 1 9 \(e\) 15 \(j\) - Here is an equation for the table: \(j = 1.25e\). What does the 1.25 mean?
- Write an equation for this relationship that starts \(e = \text{...}\)

### Solution

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(From Unit 2, Lesson 5.)