Unit 7: Geometry With Circles Day 2

Unit 7: Geometry With Circles

Lesson 2 - Circumference

What is Circumference?

Circumference is the distance around a circle.

It can be said that the circumference is the perimeter around a circle.

Multiple Choice

Check Point 1: The term for the distance around the circle is called the . . .

• Circle

• Circumference

• Di Ameter

• Radi

Circumference Relationship

• Circumference and Diameter of a circle share a relationship.

• The ratio of circumference over diameter gives a universal constant known as Pi

Multiple Choice

The ratio of circumference to diameter is a universal constant called . . .

• Theta

• Beta

• Epsilon

• Pi

Pi

• is a non-terminating decimal [it continues to go on forever]

• We use two approximations when dealing with pi:

• 22/7

• 3.14

https://i.pinimg.com/originals/92/23/e2/9223e2648ca1a652139015554f537901.gif

Pi continued

• We can calculate Pi by using the ratio:

• Circumference / diameter

Multiple Select

What is an approximation we use for pi?

• 3.29

• 22/7

• 3.15

• 3.14

• 2/7

We can use pi to find circumference.

• Circumference = pi x diameter

• C= pi x d

• Circumference = 2 x pi x radius

• C = 2 x pi x r

Ex: A pool that is 7m in diameter. Find the circumference

• We know the diameter so we can use:

• C = pi x d

• C = 3.14 x 7

• C = 21.98 m

Multiple Choice

What information is given?

• Radius is 16 km

• Circumference is 16 km

• Diameter is 16 km

Multiple Choice

Since we have diameter, what is the appropriate formula to use?

• C = pi x d

• C = 2 x pi x r

Multiple Choice

Determine Circumferencce

• C = 50 km

• C = 16 km

• C = 50.24 km