Area and Circumference of Circles

Diameter

Circumference (C) - distance around a circle (similar to perimeter)

If you measure the circumference and divide it by the diameter, the answer will always equal or 3.14...

+ +Diameter Diameter Diameter +

3.14 diameters equal circumference

= Circumference

Area and Circumference of Circles

Find the circumference of each circle using the formula. Calculator permitted. Show required steps. Use 3.14 for .

1.) 2.)

8 cm

5.1 m

Formula for circumference:

C = d or C = 2 r

14 c

m

3.) 4.)

35 m

Formula for circumference:

C = d or C = 2 r

Find the circumference of each circle using the formula. Show required steps. Leave your answer in terms of .

How many square units are in the circle? Use 3.14 for pi.

A= r2 π≈3.14

Required Steps (Calculator permitted)

A =

A =

A =

3 m

Area

Find the area of each circle. Show all required steps.

5 m

1.) (use 3.14 for pi)

2.)

7 m

(write your answer in terms of )

Find the area of each circle when the diameter is given. First find the radius, then show required steps.

12 m

3.)(use 3.14 for pi) 4.) d = 9 ft.

(write your answer in terms of )

Circles and Irregular Figures

Find the area of the shaded region.

1.) 2.)

14 ft

20 ft16 m

(use 3.14 for pi)

1.) The circular floor of the Pantheon in Rome has an area of about 1473 square meters. What is the diameter of the floor to the nearest tenth of a meter?

2.) The area of a circle is 615 cm2, what is the radius (round your answer to the nearest whole number)?

Finding the radius or diameter given the area

15 m

m

15 m

m.

Demonstrate Understanding

11 cm 8 m

1.) 2.)

Find the area and circumference for each. Use 3.14 for

3.) The area of a circle is 254 m2, what is the radius?