Circumference and Area of a Circle

​Not my favorite, but still delicious.

​​Cherry Pie

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​Love some apple pie!

​​Apple Pie

​

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Can you name four foods that are

circular in shape?

CHALLENGE QUESTION

Pizza

Donuts

Cookies

Orange

Can you name four foods that are

circular in shape?

CHALLENGE QUESTION - SAMPLE ANSWERS

Some real-world examples where
understanding circles and these
terms is essential include:
designing a circular garden,
calculating the size of a circular
pizza, or measuring the distance
around a basketball.

REAL WORLD EXAMPLES

Resist the urge for eating pie because today's lesson focuses on this exact topic. Once we learn those topics, we will end with pie.

​Some text here about the topic of discussion.

​Pi is the Best

​

Radius-the distance from the center of the circle to the outside edge.

Diameter-the distance across the circle from one edge to the other.​

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​Vocab. Review

​

The diameter is the distance across
the circle passing through its center,
connecting two points on the
opposite sides.
The measurement can be any unit of
length such as centimeters, inches,
or feet.

DIAMETER OF A CIRCLE

d

The radius is the distance from the
center of the circle to any point on
its boundary.
The measurement can be any unit
of length such as centimeters,

inches, or feet.

RADIUS OF A CIRCLE

r

r

Pi (𝛑) is a mathematical constant that

represents the ratio of a circle's

circumference to its diameter.

The approximate value of Pi (𝛑) = 3.14

It's an irrational number with infinite

decimal places

Fun Fact: March 14 ( 3/14) is known as

international Pi (𝛑) day

THE MATH SYMBOL PI (𝛑)

The diameter of a circle is two times
the radius
The letter symbol for diameter is d
The letter symbol for radius is r
The mathematical expression for the

relationship between radius and
diameter is [d = 2 x r]

RADIUS AND DIAMETER

r
d

Imagine you have a pizza with a
diameter of 14 inches. Fnd both the
circumference and the area of the
pizza.

CHALLENGE QUESTION
SAMPLE

PAGE

Given:

diameter = 14 inches

𝛑 ≈ 3.14

Solution:

If d = 14 inches then r = d ÷ 2 = 14 ÷ 2 = 7 inches

Then

C = 𝛑 x d = 14 x 3.14 = 43.96 inches

A = 𝛑 x r² = 3.14 x 7 x 7 = 153.86 inches²

CHALLENGE ANSWER

SAMPLE

PAGE

​​Circumference

​

​​Area of a Circle

​

​The circumference is the distance around a circle. Similar to finding the perimeter of a square of the rectangle.

The formula for circumference is C=πD or C=π2r

​

​The area of a circle is the region inside the edge of a circle in a 2D plane. This is just like finding the area of a square of rectangle with just a different formula.

The formula for finding the area of a circle is A=πr²​

Multiple Choice

The perimeter of a circle

• diameter

• radius

• circumference

• perimeter

Multiple Choice

The distance from one point on a circle through the center to another point on the circle.

• radius

• circumference

• diameter

Multiple Choice

the distance from the outside of a circle to the center, the radius is half the length of at the diameter.

• diameter of a circle

• pi

• radius of a circle

• cross section

Multiple Choice

the distance across the circle through the center, the diameter is twice the length of the radius.

• diameter of a circle

• radius of a circle

• pi

• angle

Multiple Choice

the distance around a circle. Can be found by using the formula C= $$\pi d$$ or C=2 $$\pi r$$  

• volume

• cross section

• circumference

• pi

Multiple Choice

the ratio of a circle's circumference to its diameter, $$\pi$$  is the symbol used of pi, and 3.14 is the approximation used for it

• cross section

• composite figure

• perimeter

• pi

Now back to pie..

​​Cherry Pie=Circumference

​

​Apple Pie=Area

​

​Cherry pies Delicious!!

​C=πD

​Apple pies are too!

A=π​r²

​That is a wrap on your lesson on Pi

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