5_Backward Work with Circle Formulas

This formula can be used when given the Circumference and needing to find the diameter.

What will you divide to find the diamter of a circle with a circumference of 42 cm?

Use 3.14 for pi

Mathematical Equivalence

ON

What is the radius of a circle with a circumference of 42 cm?

Use 3.14 for pi and round to the nearest hundredth.

Reminder:

Your answer requires a label.

What is the diameter of a circle with a circumference of 19 ft?

Use 3.14 for pi and round to the nearest hundredths place.

• 6.051 ft

• 6.06 ft

• 3.03 ft

• 6.05 ft

Your circle has a circumference of 121 mm. Which two whole numbers does the diameter fall between?

• 37 and 38

• 38 and 39

• 39 and 40

• None of these.

Your circle has a circumference of 121 mm. Which two numbers is the diameter of the circle between?

• 38.53 and 38.54

• 38.54 and 38.55

• 38.55 and 38.56

• 38.4 and 38.5

You have a circle with an area of 254 square meters. Which two whole numbers does the radius ball between?

• 7 and 8

• 8 and 9

• 9 and 10

• 8.5 and 9.0

The circle with an area of 615 square cm has a diameter that is between which two whole numbers?

• 13 and 14

• 26 and 27

• 14 and 15

• 27 and 28

The circle with an area of 1109 square inches has a radius between which two whole numbers?

• 27 and 28

• 17 and 18

• 18 and 19

• There isn't enough information.

Match the following

• Units

• Label for diameter

• Units

• Square Units

• Label for Circumference

• 25

• Label for radius

• Units

• Label for Area