Circles

Area of a Circle

100

What is the formula for the area of a circle?

A=pi x r²

200

What is the area of a circle with a radius of 15 cm?

706.5 cm

300

What is the area of circle with radius 39 cm?

1194 cm

400

What is the area of a circle with diameter 24.8 in?

482.8 in

500

What is the area of a circle with diameter 23.78 in?

443.9 in

Circumference of a Circle

100

What is the formula for circumference of a circle?

Pi x d

200

What is the circumference of a circle with a diameter of 14.8 cm?

46.5 cm

300

What is the circumference of a circle with a diameter of 41.3 cm?

129.7 cm

400

What is the circumference of a circle with a radius of 19.7cm?

123.7 cm

500

What is the circumference of a circle with radius 23.25 in?

146 in

Diameter and Radius

100

If you are given the radius, how can you find the diameter?

Multiply radius by two

200

If given the diameter, how can you find the radius?

Divide the diameter by two

300

If a circle has a radius of 15 cm, what is the diameter?

30 cm

400

If a circle has a diameter of 31 ft, what is the radius?

15.5 ft

500

A circle has a circumference of 62.8 ft, what is the diameter?

20 ft

Random

100

What numerical value is used for pi in the equation for area and circumference of circles?

3.14

200

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

Radius is half the diameter. OR Diameter is two times the radius

300

Is the exponent, 2, used in the answer for area or circumference of a circle?

Area

400

What is the diameter of a circle if the circumference is 78.5 ft?

25 ft

500

What are two ways we can write the formula for circumference of a circle?

Pi x d OR 2Pi x r