Radius and Diameter

A straight line segment that passes through the center of a circle and whose endpoints lie on the circumference of the circle is called the ____.

• Diameter

• Radius

• Circumference

• Area

A straight line from the center of a circle to the circumference is called the ____.

• Diameter

• Circumference

• Radius

• Area

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

• Radius

• Diameter

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

• Radius

• Diameter

What is the radius?

• 18

• 72

• 38

• 14

What is the radius of this circle?

• 18

• 10

• 9

• 8

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

• Radius

• Diameter

The diameter is...

• twice the radius

• half the radius

• 4 times the radius

• the radius squared

Find the diameter!

• A. 18 km

• b. 4.5 m

• C. 18 m

• D. 27 m

Swimming from one side of this pool through the center to the other side is 12 feet. What is the radius of this pool?

• 32 ft

• 6 ft

• 4 ft

• 12 ft