Area of a Circle

Area of a Circle

Remember:

1) Squaring a number means multiplying an number by itself (4² = 4 x 4 = 16)

2) Pi = 3.14

Multiple Choice

5²

• 10

• 5

• 25

Multiple Choice

7²

• 14

• 7

• 49

Multiple Choice

8²

• 64

• 16

• 8

Hint: Square the radius before multiplying by 3.14

Multiple Choice

Find the area of the circle with the given radius.

r = 6.4 in

• 40.96

• 403.8

• 128.6

Multiple Choice

Find the area of the circle with the given radius.

r = 9.4 ft

• 88.36

• 871.2

• 277.4

Multiple Choice

Find the area of the circle with the given radius.

r = 6.2

• 379

• 120.7

• 38.44

Multiple Choice

Find the area of the circle with the given radius.

r = 7.4

• 171.9

• 54.76

• 539.9

Multiple Choice

Find the area of the circle with the given radius.

r = 16

• 256

• 803.84

• 2524

Multiple Choice

Find the area of the circle with the given radius.

r = 17

• 907.46

• 289

• 2849

Multiple Choice

Find the area of the circle with the given radius.

r = 6.5

• 42.25

• 416.6

• 132.6

Multiple Choice

Find the area of the circle with the given radius.

r = 10

• 314

• 985.96

• 100

Find the radius

• 153.86 = 3.14(r²)

• Divide both sides by 3.14

• 153.86 = 3.14(r²)

• 49 = r²

• Find the square root to find r

•  $\sqrt{49}$  =  $\sqrt{r^2}$  

• 7 = r

To find the radius given the area:

• Divide by 3.14

• Square root