Lesson 12

Exploring Circumference

Diego measured the diameter and circumference of several circular objects and recorded his measurements in the table.

object	diameter (cm)	circumference (cm)
half dollar coin	3	10
flying disc	23	28
jar lid	8	25
flower pot	15	48

One of his measurements is inaccurate. Which measurement is it? Explain how you know.

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Complete the table. Use one of the approximate values for $\pi$ discussed in class (for example 3.14, $\frac{22}{7}$ , 3.1416). Explain or show your reasoning.

object	diameter	circumference
hula hoop	35 in
circular pond		556 ft
magnifying glass	5.2 cm
car tire		71.6 in

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$A$ is the center of the circle, and the length of $CD$ is 15 centimeters.

Name a segment that is a radius. How long is it?
Name a segment that is a diameter. How long is it?

A circle with center point A. Diameter CD, 15 cm. Points on the circle are C, E, G, B, D.

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(From Unit 5, Lesson 11.)

Consider the equation $y=1.5x +2$ . Find four pairs of $x$ and $y$ values that make the equation true. Plot the points $(x, y)$ on the coordinate plane.
Based on the graph, can this be a proportional relationship? Why or why not?

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(From Unit 5, Lesson 7.)

Lesson 12

Problem 1

Solution

Problem 2

Solution

Problem 3

Solution

Problem 4

Solution