Circles- Vocabulary

CIRCLES- VOCABULARY

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Radius:

This shows a circle with a radius of 50 cm, the distance from the center to the outside of the circle

Multiple Choice

What is the radius of this circle?

• 36 cm

• 9 cm

• 18 cm

• 12 cm

Diameter:

This image shows a circle with a diameter of 12 inches, the distance from one side to the other going through the center.

Multiple Choice

What is the diameter of this circle? 

• 10 cm

• 5 cm

• 2.5 cm

• 50 cm

Radius and Diameter

• The diameter is twice the radius so: Diameter = Radius x 2

• The radius is half the diameter so: Radius = Diameter divided by 2

Multiple Choice

This image shows the radius of a circle, what is the circles diameter?

• 10 m

• 5 m

• 12 m

• 15 m

Multiple Choice

This circle shows the diameter, what is the radius of this circle?

• 12 cm

• 10 cm

• 5 cm

• 6 cm

Circumference of a Circle

This image shows that circumference is the distance around the entire circle - the red lines length

Multiple Choice

The _______ of a circle is the distance around the circle.

• radius

• diameter

• circumference

What is Pi?

• the ratio of the circumference to the diameter of a circle (π= c/d)

• a greek symbol (π)

• approximately 3.14

• used when solving area and circumference of circles

Multiple Select

What is pi?

Check ALL applicable answers!

• a delicious dessert

• the ratio between circumference and diameter

• a Greek symbol

• exactly 3.14

• approximately 3.14

Area

• the measure inside the circle

• always in square units

• A = π r²

NoW LET'S REVIEW & PRACTICE WHAT WE LEARNED TODAY...

Multiple Choice

What is the diameter of this circle?

• 3.5

• 7

• 14

• 6

Multiple Choice

A _______ is a line segment that goes from the center to the edge of a circle.

• radius

• diameter

• circumference

Multiple Choice

A _______ is a line segment that goes from one edge of a circle to the other and passes through the center.

• radius

• diameter

• circumference

Multiple Choice

A pond has a diameter of 12 feet. What is its radius?

• 12 feet

• 6 feet

• 24 feet

Multiple Choice

A tire has a radius of 14 inches. What is its diameter?

• 14 inches

• 7 inches

• 28 inches

Multiple Choice

pi is about...

• 6.14

• 1,000,000,000,000

• 3.14

• 0.1

Multiple Choice

If you are given the diameter, how can you calculate the radius?

• Multiply the diameter by 2

• Divide the diameter by 2

• Add 2 to the diameter

• Subtract 2 from the diameter

Multiple Choice

Identify the part of the circle.

• arc

• center

• chord

• point of tangency

• sector