Lesson 3
Exploring Circumference
Let’s explore the circumference of circles.
Problem 1
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.
Problem 2
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 |
Problem 3
\(A\) 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?
Problem 4
-
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?