Circumference & Area of Circles Quick Check
1 of 51 of 5 Items
Question
Which of the following uses the correct formula to find the approximate circumference of a circle that has a radius of 12? Use 3.14 for π and express your answer to the hundredths place.(1 point)
Responses
18.84
18.84
37.68
37.68
75.36
75.36
452.16
37.68
Circumference & Area of Circles Quick Check
2 of 52 of 5 Items
Question
Which of the following uses the correct formula to find the approximate circumference of a circle that has a radius of 450?(1 point)
Responses
C≈3.14⋅4502
upper C approximately equals 3.14 times 450 squared
C≈3.14⋅450÷2
upper C approximately equals 3.14 times 450 divided by 2
C≈2⋅3.14⋅450
upper C approximately equals 2 times 3.14 times 450
C≈3.14⋅150
upper C approximately equals 3.14 times 150
C≈2⋅3.14⋅450
upper C approximately equals 2 times 3.14 times 450
Circumference & Area of Circles Quick Check
3 of 53 of 5 Items
Question
Which formula correctly describes the proportional relationship between the circumference of a circle and the diameter?(1 point)
Responses
C=πd
upper C equals Start Fraction pi over d End Fraction
π=dC
pi equals Start Fraction d over upper C
A=πr2
upper A equals pi r squared
Cd=π
Start Fraction upper C over d End Fraction equals pi
C=πd
upper C equals π times d
Use the correct formula to find the area of a circle if the diameter is 21 mi. Round to the nearest hundredths place. Use 3.14 for π .(1 point)
Responses
1,384.74 mi.2
1,384.74 mi squared
346.19 mi.2
346.19 mi squared
131.88 mi.2
131.88 mi squared
65.94 mi.2
To find the area of a circle, we use the formula A = πr^2, where r is the radius. Since the diameter is given, we first need to find the radius by dividing the diameter by 2.
Radius (r) = Diameter / 2
Radius = 21 mi / 2
Radius = 10.5 mi
Now we can use the formula for the area:
A = π(10.5)^2
A = 3.14 * 110.25
A ≈ 346.19 mi^2
Therefore, the correct answer is:
346.19 mi^2
A=πr^2
upper A equals π times r squared
Circumference & Area of Circles Quick Check
5 of 55 of 5 Items
Question
Which of the following is the correct formula for finding the area of a circle?(1 point)
Responses
A=πr2
upper A equals pi r squared
A=2πr
upper A equals 2 pi r
A=C2÷4πA=πd2
upper A equals upper C squared divided by 4 pi upper A equals pi d squared
A=πd