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.

Photo of a ferris wheel.

  1. On the picture, draw and label a diameter.

  2. 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.

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

  2. The distance across a sink drain is 3.8 cm.

  3. The tires on a mining truck are 14 ft tall.

  4. The fence around a circular pool is 75 ft long.

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

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

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

  8. 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?

The figure shows a half circle and a triangle.

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?

(From Unit 3, Lesson 3.)