Circles and Pi

If the diameter of a circle is 9cm, we can ESTIMATE that the circumference will be a little more than:

• 27cm

• 3cm

Answer explanation

The question asks for an estimate of the circumference of a circle with a diameter of 9cm. The formula to calculate the circumference of a circle is π*diameter. Assuming π as 3 (for simplicity), the estimated circumference will be 3*9=27cm. Therefore, the correct choice is a little more than 27cm.

If the circumference of a circle is 9cm, we can estimate that the diameter will be about:

• 3cm

• 27cm

Answer explanation

The question asks for the approximate diameter of a circle given its circumference is 9cm. The formula to find the diameter is: Diameter = Circumference/π. Using an estimation of 3 for π, we get a diameter of approximately 3cm. Thus, the correct answer is 3cm.

The radius is what of the diameter

• twice

• half

• equal

• undetermined

If the diameter of a circle is 15, the radius is

• 30

• 7.5

• 15

• 20

If the radius of a circle is 10, what is the diameter?

• 10

• 5

• 20

• 15

Which is not part of a circle?

• diameter

• radius

• pi

• angle

the ratio of a circles circumference to its diameter

• area

• circumference

• pi

• radius

Pi equals

• 22/7

• approximately 3.14...

• The ratio of the diameter to the radius of a circle

• The ratio of the circumference to the diameter of a circle

• The ratio of the circumference to the radius of a circle

Another name for the distance around a circle or the perimeter of a circle is called the........

• circumference

• equidistance

• area

• radius

The distance around a circle

• area

• diameter

• circumference

• radius