Area & Circumference of Circles

Area & Circumference of Circles

Dr. Tom Giles

​Math Antics Circles, Circumference, & Area

The area of a circle is equal to the radius of the circle squared times pi.

​​Area Formula

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The circumference of a circle is equal to the diameter of the circle times pi or the radius times two multiplied by pi.

​​Circumference Formula

Multiple Choice

What is the circumference of a circle with diameter 10cm?

• 10π cm

• 20π cm

• 5π cm

• 100π cm

Multiple Choice

What is the circumference of a circle with radius 6cm?

• 12π cm

• 36π cm

• 18π cm

• 6π cm

Multiple Choice

A circular table has a radius of 1.5m. What is the circumference of the table to the nearest meter?

• 9m

• 3m

• 4m

• 7m

Fill in the Blanks

Find the circumference for the circle. Leave your answer in terms of pi.

Fill in the Blanks

Find the circumference for the circle. Round your answer to the nearest hundredth.

Multiple Choice

What is the circumference of a circle with diameter 18cm?

• 18π cm

• 9π cm

• 36π cm

• 28π cm

Multiple Choice

A circular garden has a radius of 5m. How many meters of fencing would be needed to surround the garden completely?

• 10π m

• 15π m

• 25π m

• 50π m

Multiple Choice

What is the formula for the area of a circle with radius r?

• A = 2πr
• A = πr^2
• A = πd
• A = 2r

Multiple Choice

What is the area of this circle?

• 4π

• 8π

• 16π

• π

Multiple Choice

A circular rug has a radius of 2.5m. What is the circumference of the rug to the nearest meter?

• 16m

• 5m

• 8m

• 20m

Fill in the Blanks

Find the area of the circle. Leave your answer in terms of pi.

Fill in the Blanks

Find the area of the circle. Round your answer to the nearest hundredth.

Fill in the Blanks

Find the area for the circle. Leave your answer in terms of pi.

Multiple Choice

What is the area of a circle with diameter 14cm?

• 49π cm^2

• 196π cm^2

• 98π cm^2

• 28π cm^2

Fill in the Blanks

Find the area for the circle. Round your answer to the nearest tenth.

Fill in the Blanks

Find the area for the circle. Leave your answer in terms of pi.

Multiple Choice

What is the area of a circle with radius 8cm?

• 16π cm^2
• 64π cm^2
• 128π cm^2
• 32π cm^2

Fill in the Blanks

Find the area for the circle. Round your answer to the nearest tenth.

Multiple Choice

A pizza has a diameter of 20cm. What is the area of the pizza to the nearest square centimeter?

• 314 cm^2

• 201 cm^2

• 100 cm^2

• 1256 cm^2

Fill in the Blanks

Find the area for the circle. Leave your answer in terms of pi.

Fill in the Blanks

Find the area for the circle. Round your answer to the nearest hundredth.

Multiple Choice

A circular fountain has a diameter of 8m. What is the area of the water surface to the nearest square meter?

• 50m^2
• 201m^2
• 100m^2
• 25m^2

Fill in the Blanks

Find the circumference for the circle. Leave your answer in terms of pi.

Multiple Choice

What is the area of a circle with radius 3cm?

• 3π cm^2
• 6π cm^2
• 9π cm^2
• π cm^2

Fill in the Blanks

Find the circumference for the circle. Round your answer to the nearest hundredth.

Multiple Choice

A circular pond has a radius of 12m. What is the circumference of the pond to the nearest meter?

• 38m
• 24m
• 75m
• 48m

Fill in the Blanks

Find the circumference for the circle. Leave your answer in terms of pi.

Multiple Choice

A circular pool has a diameter of 6m. What is the area of the pool to the nearest square meter?

• 28m^2

• 9m^2

• 3m^2

• 12m^2

Fill in the Blanks

Find the circumference for the circle. Round your answer to the nearest hundredth.

Multiple Choice

A circular trampoline has a diameter of 4.5m. What is the area of the trampoline to the nearest square meter?

• 16m^2
• 6m^2
• 64m^2
• 32m^2

Fill in the Blanks

Find the circumference for the circle. Leave your answer in terms of pi.

Multiple Choice

What is the formula for the circumference of a circle with radius r?

• C = 2πr
• C = πr^2
• C = πd
• C = 2r

Fill in the Blanks

Find the circumference for the circle. Round you answer to the nearest hundredth.

Fill in the Blanks

Find the diameter of a circle with a circumference of 65.97 meters.

Use $C=\pi d$   to find the diameter of the circle.

What is the diameter of the circle? Round your answer to the nearest whole number.

Fill in the Blanks

Find the radius of a circle with a circumference of 21.99 meters.

Use $C=2\pi r$  to find the radius of the circle.

What is the radius of the circle? Round your answer to the nearest tenth.

Fill in the Blanks

Find the radius of a circle with a circumference of 35 $\pi$  meters.

Use $C=2\pi r$  to find the radius of the circle.

What is the radius of the circle? Round your answer to the nearest tenth.

Fill in the Blanks

Find the radius of a circle with an area of 380.13 square inches.

Use $A=\pi r^2$  to find the radius of the circle.

What is the radius of the circle? Round your answer to the whole number.

Fill in the Blanks

Find the diameter of a circle with an area of 615.75 centimeters squared.

Use $A=\pi r^2$  to find the diameter of the circle.

What is the diameter of the circle? Round your answer to the whole number.

Fill in the Blanks

Find the diameter of a circle with an area of 90.25 $\pi$  centimeters squared.

Use $A=\pi r^2$  to find the diameter of the circle.

What is the diameter of the circle? Round your answer to the whole number.

Fill in the Blanks

Find the area of a circle with a circumference of $26\pi$   feet. Round your answer to the nearest hundredth.

Fill in the Blanks

Find the circumference of a circle with an area of $289\pi$   feet. Round your answer to the nearest hundredth.

Fill in the Blanks

Find the circumference of a circle with an area of 113.1 inches squared. Round your answer to the nearest tenth.

Fill in the Blanks

Find the area of a circle with a circumference of 131.95 meters. Round your answer to the nearest hundredth.

Fill in the Blanks

Find the area of a circle with a circumference of 18.84 meters. Round your answer to the nearest hundredth.

Fill in the Blanks

Find the circumference of a circle with an area of 1,809.56 square centimeters. Round your answer to the nearest tenth.