Understanding Circles: Radius and Diameter

What is the radius of a circle with a diameter of 10 cm?

• 3 cm

• 5 cm

• 10 cm

• 7 cm

If the radius of a circle is 5 cm, what is its diameter?

• 10 cm

• 15 cm

• 12 cm

• 8 cm

Draw a circle with a radius of 4 cm. How did you measure it?

• A circle with a radius of 4 cm was drawn freehand.

• A circle with a radius of 4 cm was drawn using a protractor.

• A circle with a radius of 4 cm was drawn using a compass.

• A circle with a radius of 4 cm was drawn using a ruler.

What do you call the distance across a circle through its center?

• Radius

• Circumference

• Diameter

• Chord

If a circle has a diameter of 12 cm, what is its radius?

• 10 cm

• 4 cm

• 8 cm

• 6 cm

Explain why the radius is half of the diameter.

• The radius is equal to the diameter.

• The diameter is half of the radius.

• The radius is twice the diameter.

• The radius is half of the diameter.

Draw a circle with a diameter of 8 cm. What tools did you use?

• Calculator and string

• Eraser and paper

• Protractor and pencil

• Compass and ruler

If the radius of a circle is 3 cm, what is the circumference?

• 12.56 cm

• 9.42 cm

• 25.13 cm

• 18.85 cm

What is the relationship between radius and diameter in a circle?

• The diameter is half the radius.

• The radius and diameter are equal.

• The radius is twice the diameter.

• The diameter is twice the radius.

If you double the radius of a circle, what happens to the diameter?

• The diameter decreases by half.

• The diameter triples.

• The diameter remains the same.

• The diameter also doubles.