Finding the Circumference of a Circle Using Radius and Diameter

The radius of the circle is 9cm.

C = 2πr

C = 2π9

Based on the previous steps, what should you write next?

• C = 18π
• C = 9π
• C = 2π18
• C = 3π

The radius of the circle is 9cm.

C = 2 x π x r

C = 2 x π x 9

Based on the previous steps, what is the approximation of the circumference?

Use 3.14 for π.

• 56.52cm
• 67.38cm

• 36.17cm

• 53.42cm

The diameter of the circle is 12ft.

C = d x π

C = 12 x π

Based on the previous steps, what is the circumference of the circle?

Use 3.14 for π.

• 25.12ft
• 30.48ft
• 42.56ft
• 37.68ft

The diameter of the circle is 12ft.

C = d x π

C = 12 x π

Based on the previous steps, what is the circumference of the circle?

Use 3.14 for π.

• 37.68ft
• 30.24ft
• 40.56ft
• 25.12ft