Circumference Radius of a Circle

Other than the formula C=πd what is another formula for circumference of a circle?

• C=2π

• C=2πr

• C=πr²

• C=πd²

If the problem ask you to find the distance around a circle, which formula should you use?

• r = 1/2d

• d = 2r

• C = πd

• A = πr²

what is the circumference of this circle ?

• 3.14 cm 

• 37.68 cm

• 24 cm

• 68.4 cm

Radius 4 inches
Find the circumference of the circle. 

• 25.12 in

• 12.56 in

• 50.24 in

• 200.96 in

Ray wants to build a fence around his circular garden outside. The garden has a radius of 6 ft. How many feet of fencing does he need?

• 37.68 ft

• 18.84 ft

• 113.04 ft

• 452.16 ft

What is the diameter?

• 8

• 16

• 10

• 4

What is the radius?

• 18

• 72

• 38

• 14

Radius 6 cm
What is the diameter? 

• 36 cm

• 12 cm

• 6 cm

• 3 cm 

Diameter 32 inches
What is the radius?

• 16 inches

• 64 inches

• 96 inches
  96 inches

• 16 ft 

What formula is this used for:
πd

• Area

• Circumference 

• Surface Area

• Volume