Understanding the Area of a Circle

What is the formula used to calculate the area of a circle?

• A = 2πr

• A = πr²

• A = πd

• A = 2πd

If the radius of a circle is 5 decimeters, what is the area?

• 78.5 square decimeters

• 50 square decimeters

• 100 square decimeters

• 25 square decimeters

How do you calculate the area of a circle with a radius of 9 inches?

• 81 square inches

• 254.34 square inches

• 162 square inches

• 100 square inches

What is the relationship between the diameter and radius of a circle?

• Diameter is three times the radius

• Diameter is equal to the radius

• Diameter is twice the radius

• Diameter is half the radius

If the diameter of a circle is 12 inches, what is the area?

• 113.04 square inches

• 36 square inches

• 72 square inches

• 144 square inches

What formula is used when the diameter is given instead of the radius?

• A = πd²

• A = π(d/2)²

• A = 2πd

• A = πd

What is the approximate value of π used in these calculations?

• 3.14

• 3.50

• 3.00

• 3.75

Which formula should be used if the radius is provided?

• A = 2πr

• A = πd

• A = πr²

• A = πd²

Which formula should be used if the diameter is provided?

• A = πd²

• A = 2πr

• A = πr²

• A = π(d/2)²

What is the area of a circle with a radius of 7 inches?

• 100 square inches

• 153.86 square inches

• 49 square inches

• 200 square inches