Unit 3: Measuring Circles
3848.45... square miles
A cell phone tower picks up signals within a 70 mile diameter. How many square miles of coverage does the cell tower provide?
56.25π
A circle has a circumference of 47 cm. What is the area in terms of pi? Round to the nearest whole number as needed.
36π
A circle has a diameter of 12 cm. What is the area in terms of pi?
50.265...ft
A circle has an area of 201.6 feet. What is the circumference? Round as needed.
254.469...ft²
A circular fountain has a diameter of 18 feet. What is the area?
All diameters are chords because they connect two points on the circumference like a chord. Not all chords are diameters because not all chords pass through the center.
All diameters are chords, but not all chords are diameters. Explain.
64π
An architect is making a plan for a new circular playground. The picture shows a drawing of the playground. How much fencing needs to go up to around the edge of the playground? Keep in terms of pi.
31 3/7
Brad is putting up a 5 foot radius circular flower garden in his yard. He will put plastic edging along the flowerbed. How many feet of edging will Brad need to enclose his flower garden? Use 22/7 for pi.
diameter
Connects 2 points on circumference and passes through the center point; twice the radius of a circle.
A diameter is a chord because both connect 2 points on the circumference. A radius is not a chord because it connects only 1 point on the circumference.
Explain why a diameter is chord, but a radius is not.
75.36
Find the circumference using 3.14 for pi.
81.681...ft
Find the circumference.
πr²
Formula for finding area of a circle.
½πr²
Formula for finding area of a semi-circle.
14.5π
Jim's frying pan is 14.5 inches in diameter. What is the circumference of his frying pan in terms of pi?
22 inches
Macy measures a truck's tire mark for one complete revolution as 69.08 inches long. What is the diameter of the tire using 3.14 for pi?
18.84 inches
The area of a circle is 28.26 inches. What is the circumference? Use 3.14 for pi.
6 ft.
The area of a circle is 28.26 square feet. What is the diameter? Use 3.14 for pi.
803.84 square meters
The circumference of a circle is 100m. What is the area? Use 3.14 for pi. Round to the nearest whole number as needed.
5.5 inches
The circumference of a circle is 34 inches. What is the radius? Use 3.14 for pi.
785.4
The first ferris wheel was built in 1893 in Chicago. The diameter was 250 feet. How many feet did the ferris wheel rotate with one complete turn rounded to the nearest tenth?
35.668...
Trevor needs a new bicycle tire. His tire has a circumference of 112 inches. What is the diameter of his tire? Use 3.14 for pi.
circumference
distance around the edge/outside of a circle
radius
distance from the center to any point on the circle; ½ diameter of a circle
𝝅d OR 2πr
formula to find the circumference of a circle
2r
formula to find the diameter of a circle
d/2
formula to find the radius of a circle
circle
set of points in a plane which are the same distance from the center
center
the middle of a circle
semicircle
½ of a circle
