Circumference 1

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

Find the radius of a circle whose diameter is 40 ft.

• 40ft

• 80ft

• 20ft

• 45ft

What is the circle's radius?

• 5 cm

• 10 cm

• 20 cm

What is the formula for the CIRCUMFERENCE of a circle?

• $C=\pi r^2$

• $C=\pi r$

• $C=2\pi r$

• $C=2\pi d$

To find pi we divide:

• Diameter/Circumference

• Circumference/Diameter

• Circumference/Radius

• Circumference/Radius

What does "circumference" mean?

• Space a circle takes up
• Distance around a circle
• Line from one side of a circle to another
• Line from center of circle to side

What number is pi?

• 1.41

• 2.00

• 3.14

• 5.14

What is the radius of a circle when the diameter is 70 m?

• 38

• 35

• 90

• 140

A cruise ship has a large, circular window. It has a diameter of 6 meters. What is the window's approximate circumference?

Hint: 

 $C=2\pi r$  
Use 3 as $\pi$  and choose the answer that is the closest. 

• 3 m 

• 9.42 m

• 12 m

• 18.84 m