Circumference and Area of Circles

What are the formulas for circumference of a circle?

• C = π r

• C = π d

• C = 2 π r

• C = 2 π d

How do you find the area of a circle?

Find the area of this Semicircle with a diameter of 18 cm

• 254.34 cm

• 127.17 cm

• 56.52 cm

• 28.26 cm

Find the perimeter of the semicircular region. Round your answer to the nearest hundredth.

• 23.13 m

• 28.26 m

• 14.13 m

• 56.52 m

What is the area of the square that is not covered by the pink circle? (use 3.14 for pi)

• 78.5 in²

• 21.5 in²

• 31.4 in²

• 68.6 in²

Find the circumference of a circle with a radius of 12.5 mm .

• 37.68mm

• 18.84mm

• 78.5mm

• none of the above

What is π ? (Best Choice)

• The ratio of the circumference of any circle to its diameter.

• Exactly 3.14

• Exactly 3.1415

• Exactly 3.141593

The circumference is 62.8 inches. What is the radius? (Use 3.14 for π)

• 20 inches

• 10 inches

• 6.28 inches

• 31.4 inches

Find the circumference of a circle with a diameter of 11 millimeters.

• 34.6 mm

• 30 mm

• 25.3 mm

• 34.54 mm

Elsie bought a circular rug that is 9 feet in diameter. What is the circumference of the rug rounded to the nearest tenth of a foot?

• 4.5 feet

• 14.1 feet

• 28.3 feet

• 56.5 feet