Lesson 4
Applying Circumference
Let’s use \(\pi\) to solve problems.
Problem 1
Here is a picture of a Ferris wheel. It has a diameter of 80 meters.

On the picture, draw and label a diameter.

How far does a rider travel in one complete rotation around the Ferris wheel?
Problem 2
Identify each measurement as the diameter, radius, or circumference of the circular object. Then, estimate the other two measurements for the circle.

The length of the minute hand on a clock is 5 in.

The distance across a sink drain is 3.8 cm.

The tires on a mining truck are 14 ft tall.

The fence around a circular pool is 75 ft long.

The distance from the tip of a slice of pizza to the crust is 7 in.

Breaking a cookie in half creates a straight side 10 cm long.

The length of the metal rim around a glass lens is 190 mm.

From the center to the edge of a DVD measures 60 mm.
Problem 3
A half circle is joined to an equilateral triangle with side lengths of 12 units. What is the perimeter of the resulting shape?
Problem 4
Circle A has a diameter of 1 foot. Circle B has a circumference of 1 meter. Which circle is bigger? Explain your reasoning. (1 inch = 2.54 centimeters)
Problem 5
The circumference of Tyler's bike tire is 72 inches. What is the diameter of the tire?