Exploring Circumference and Area of Circles

What formula is used to calculate the circumference of a circle when the diameter is known?

• Circumference = pi * radius^2

• Circumference = 2 * pi * radius

• Circumference = 2 * radius

• Circumference = pi * diameter

If the diameter of a circle is 10 cm, what is the approximate circumference?

• 31.4 cm

• 20 cm

• 62.8 cm

• 15.7 cm

What is the formula for calculating the area of a circle?

• Area = pi * radius^2

• Area = pi * diameter^2

• Area = 2 * pi * radius

• Area = radius * radius / pi

If the radius of a circle is 9 inches, what is the approximate area?

• 254.34 square inches

• 81 square inches

• 28.26 square inches

• 567.56 square inches

For a circular landing pad of radius 20 meters, what is the closest length of tape needed to go around it?

• 125.6 meters

• 62.8 meters

• 40 meters

• 314 meters

When calculating the area of a circle with a diameter of 34 inches, what is the first step?

• Multiply diameter by pi

• Square the diameter

• Multiply the diameter by 2

• Divide the diameter by 2 to find the radius

What is the area of a circle with a radius of 17 inches?

• 289 square inches

• 34 square inches

• 3.14 square inches

• 907.46 square inches

If the radius of a circular mirror is 21 inches, what is the closest area?

• 84 square inches

• 1385 square inches

• 3.14 square inches

• 441 square inches

For a party hat with a circular opening radius of 8 cm, what is the circumference?

• 50.24 cm

• 16 cm

• 100.48 cm

• 25.12 cm

What is the circumference of a circular CD with a diameter of 120 mm?

• 753.6 mm

• 376.8 mm

• 60 mm

• 240 mm