Vocab
Circumference
Area
Real-World Problems
I'm Going to Ace this Test
100
Define radius.
A line in the circle that goes from the center to the circumference.
100

What is the formula for the circumference of a whole circle?

c=πd or c=π2r

100
What is the formula for area of a circle?
a=πr²
100
Anna is planting a circular garden. If the diameter of the garden is 21 meters, what is the circumference? Use 3.14 for π.
65.94 m
100

If a circle has a radius of 5 cm, what is it's diameter?

10 cm

200
Define diameter.
A line in a circle that passes through the center and touches two places on the circumference.
200

Find the circumference of a circle with a diameter of 16 in using 3.14 for π. Round to the nearest hundredth if necessary.


50.24in

200
Find the area of a circle with a radius of 31.5 cm. Use 22/7 for π.
3118.5 cm²
200

The face of a circular sundial has a diameter of 18 inches. Find the area of the brass needed to cover one side of the sundial. Use 3.14 for π.

(hint: think about what one side of a circle is called)

254.34 in²

200

The circumference measures the _________ of the circle.

Edge/Outside

300

Define Circumference.

The distance around the whole circle.

300
Find the circumference of a circle with a radius of 17 in using 3.14 for π. Round to the nearest tenth.
106.8 in
300
Find the area of a circle with a radius of 3.4 m. Use 3.14 for π. Round to the nearest tenth.
36.3 m²
300
A store sells a circular rug that has a diameter of 8 ft. Find the amount of material needed to make this rug. Use 3.14 for π and round to the nearest tenth.
50.2 ft ²
300
If a circle has a diameter of 14 feet, what is its radius?

7 feet 

400
A semicircle is ________ of a circle.
half
400
Find the length of the arc of a semicircle that has a diameter of 5 in. Use 3.14 for π.
7.85 in
400
Find the area of a circle with a diameter of 11.6 m. Use 3.14 for π. Round to the nearest tenth.
105.6m².
400

Teresa is making a card for her mom. The card is in the shape of a circle and has a diameter of 7 in. She wants to put ribbon around the edge of her card. How much ribbon will she need?

(Hint: what is another term we could use instead of around the edge?)

21.98 in

400
What are the two most commonly used estimates for π?
3.14 and 22/7
500

What is the difference between the area of circle and the perimeter of a circle.

Area of a circle is the space taken up inside the circle. The perimeter is the distance around the circle.

500

Find the perimeter around a semicircle that has a radius of 11 in. Use 3.14 for π.

56.54 in

500

Find the area of a semicircle with a diameter of 14 in. Use 22/7 for π.

77in².

500
Riggoletto's Portraits specializes in making circular portraits of people. A large portrait is 30 inches in diameter. A medium portrait is 10 inches in diameter. Estimate the difference between the areas of the two sizes of portraits. Use 3.14 for π. Round your answer to the nearest whole number.
About 628 in²
500

If a Circle has a diameter of 81 meters, what is it's radius

9 meters

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