Circumference of a Circle

Circumference of a Circle

First Review of a Circle...

Radius

Distance from the center to any point on the outside of the circle.

Definition:

Draw

What does the radius of a circle look like?

Diameter

Distance from one side of the circle to the other that goes through the center

Definition:

Draw

What does the diameter of a circle look like?

What is the relationship between radius & diameter?

Poll

Do you know what circumference is?

• Yes, I have heard of it before but remember nothing about it

• Yes, I remember it

• No I have never heard of it

C= πd or C=2πr

​Formula:

Distance around a Circle; Special word for perimeter

Definition:

What is Circumference?

Poll

What is the circumference of a circle?

• Area of a circle

• Special word for perimeter of a circle

• Special word for radius of a circle

• Special word for diameter of a circle

Multiple Choice

Find the circumference of the circle with a diameter of 3. Find the exact circumference using pi. Round to the nearest hundredth.

• 3π

• 9.42

• 3

• 3.14

Multiple Choice

Find the circumference of the circle with a radius of 3. Find the exact circumference Round to the nearest hundredth.

• 18.84

• 6π

• 18.85

Multiple Choice

Example 3: Bernard works at a community center that has a circular swimming pool with a circumference of 40 meters. He would like to use a rope to divide the pool down the center. What should be the length of the rope? Round to the nearest hundredth.

• 12.73 m

• 125.66 m

• 12.74 m

• 125.67 m