ACT Prep: Circle Area & Circumference

What is the circumference, in inches, of a circle with a radius of 8 inches?

• 4π

• 8π

• 12π

• 16π

• 64π

The circle shown has a diameter of 14 inches. What is the circumference of the circle, in inches?

• 7π

• 14π

• 28π

• 49π

• 196π

The perimeter of circular field is 500 feet. Which of the following is closest to the radius of the field, in feet?

• 10

• 50

• 80

• 160

• 250

Circles A, B, and C have radii with measures of x centimeters, 3x centimeters, and 6x centimeters, respectively. What is the ratio of the radius of Circle B to the diameter of Circle C?

• 1:2

• 1:4

• 1:12

• 2:1

• 4:1

If a circle has a circumference of 108π inches, how many inches long is its radius?

• √108

• 27

• 54

• 108

• 216

If a circle has a circumference of 6/5 π centimeters, how long is its radius, in centimeters?

• 3/5

• 5/6

• 6/5

• 5/3

• √6/5

A circle that lies on the standard (x,y) coordinate plane has its center at (8,-6) and passes through the origin. What is the area of this circle, in square coordinate units?

• 14π

• 20π

• 36π

• 64π

• 100π

Richard brought his dog to the park and tied his leash to a flagpole while he had a picnic. The dog could reach 12 feet from the flagpole in any direction. What is the approximate area of the ground, in square feet, that the dog could reach from the flagpole?

• 19

• 38

• 75

• 113

• 452

The figure shows four congruent semicircles that touch only at the corners of a square. The path from point X, along the diameters of the semicircles, back to point X is 96 inches long. How long is the path from point X, along the arcs of the semicircles, back to point X, in inches?

• 24π

• 48π

• 96π

• 144π

• 288π

The figure shows a small circle with a diameter (line AC) and a large circle with a diameter (line AB) that is 32 inches long. Point C is the center of the large circle. What is the area, in square inches, of the small circle?

• 8π

• 16π

• 32π

• 40π

• 64π