Understanding the Area of Circles

What is the formula for the area of a circle?

• A = 2πr²

• A = πr

• A = πr²

• A = 2πr

If the radius of a circle is 17 ft, what is the area of the circle rounded to the nearest tenth?

• 97.46 ft²

• 289 ft²

• 510 ft²

• 97.5 ft²

What common mistake should be avoided when squaring the radius?

• Dividing the radius by 2

• Adding the radius to itself

• Subtracting the radius from itself

• Multiplying the radius by 2

How do you find the radius if you are given the diameter of a circle?

• Subtract 2 from the diameter

• Multiply the diameter by 2

• Divide the diameter by 2

• Add 2 to the diameter

If a circle has a diameter of 8.31 cm, what is the radius?

• 8.31 cm

• 2.07 cm

• 16.62 cm

• 4.15 cm

What is the formula for the area of a semicircle?

• A = πr

• A = 2πr

• A = 1/2 πr²

• A = πr²

If the radius of a semicircle is 10, what is the area of the semicircle?

• 100

• 628

• 157

• 314

How do you find the area of a rectangular mat with a circular cutout?

• Divide the area of the rectangle by the circle

• Multiply the area of the rectangle by the circle

• Subtract the area of the circle from the rectangle

• Add the area of the rectangle and the circle

What is the area of a rectangle with dimensions 18 by 12?

• 144

• 30

• 216

• 2160

If a circle has a radius of 4, what is its area?

• 12.56

• 25.12

• 16

• 50.24