Circles Basics

Circle Introduction

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Vocab

• A circle is a round shape with no corners or edges.

• The center is in the middle of the circle. It is the same distance to any point on the outside of the circle.

• The radius is the distance from the center to the outside of the circle.

• The diameter is the distance across the entire circle through the center.

Multiple Choice

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

Multiple Choice

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

Multiple Choice

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

Multiple Choice

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

Multiple Choice

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

Multiple Choice

A line that starts from the center of a circle and ends at the edge is called ...

• Radius

• Diameter

Multiple Choice

Does this picture show the diameter or radius of a circle?

• Diameter
• Radius

Multiple Choice

Is this a picture of the diameter?

• Yes

• No

Multiple Choice

If you draw line through the center of the circle, to its edges, that can be called its ...

• Radius

• Diameter

Multiple Choice

If my radius is 10ft, what is my diameter?

• 20ft

• 5ft

• 31.4ft

• 62.8ft

Multiple Choice

If the radius of this circle is 9.5 inches, what is its Diameter?

• 19 inches

• 9.5 inches

• 4.75 inches

• 83.5 inches

Multiple Choice

The Diameter of this circle is 23.4 miles. What is the measurement of the radius?

• 11.7 miles

• 11.7 inches

• 46.8 miles

• 23.4 miles

Multiple Choice

If QR is 7.2 meters, what is the Diameter of this circle?

• 14.4 meters

• 7.2 meters

• 3.6 meters

• 52 meters

Formulas

C = 3.14 x diameter​

Circumference​

A = 3.14 x radius x radius

Area

Multiple Choice

If the radius of this circle is 4, what is the AREA?

A = 3.14 x radius x radius

• 50.24

• 16

• 12.56

• 3.14

Multiple Choice

If the radius of this circle is 1, what is the CIRCUMFERENCE?

C= 3.14 X diameter

• 6.28

• 16

• 12.56

• 3.14