7th Circumference and Area

Circumference and Area of Circles

​Circles

What is Circumference

Distance around the circle

Formulas We will use for circles

​C = 2πr

or

C = πd

​A = πr² ​ π = 3.14​

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Some text here about the topic of discussion

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Multiple Choice

What is the diameter?

• 8

• 16

• 10

• 4

Multiple Choice

What is the radius?

• 18

• 72

• 38

• 14

Multiple Choice

What is the radius of this circle?

• 12cm

• 6cm

• 24cm

• 3cm

We will focus on finding the circumference of a circle. The circumference is the distance around a circle (like the perimeter), so it is measured in units such as "inches", "feet", "centimeters", etc.

NOT square units!

Unlike area, there are two formulas that can be used to find the circumference of a circle:

One when given the diameter

and

One when given the radius.

Now, you will try one on your own!

Fill in the Blanks

Now, you will try one on your own!

Fill in the Blanks

Parts of a Circle

An important question.

Multiple Choice

I wrapped a tape measure around the trunk of the tree and it was 10 feet. What is the diameter of the tree? Use 3.14 for pi. Round to the nearest hundredth.

• 1.59 ft

• 31.4 ft

• 3.18 ft

• 10.11 ft

Fill in the Blanks

Multiple Choice

A circular pie has an area of 706.5 cm². What is the radius of the pie?

• 225 cm

• 30 cm

• 15 cm

• 112.5 cm