Question

The diameter of the larger circle is 12.5 cm.
The diameter of the smaller circle is 3.5 cm.

What is the approximate area of the shaded region?





A.


28.26 cm²


B.


113.04 cm²


C.


132.27 cm²


D.


254.34 cm²

Answer 1

I tried to get the answer by doing \[12.5 \times 3.5 but \it turned out \to be 43.75 which was \not there. ;-; sadly\]

Answer 2

woah that was weird

Answer 3

@gaos

Answer 4

@pinklion23

Answer 5

@Whitemonsterbunny17

Answer 6

@geerky42

Answer 7

Area of the greater circle- area of the smaller circle
πRadius^2-πradius^2

Answer 8

6.28

Answer 9

3.14x(12.5)^2 - 3.13x(3.5)^2

Answer 10

You just need to find area of big circle and small circle using \(A = \pi r^2\)

THEN you subtract big circle by small circle.

Answer 11

First convert diameter into radius

Answer 12

how do i do that?

Answer 13

Let's just find area of bigger circle.

diameter is 12.5

So what is radius?

Answer 14

:/ radius is....a line segment that joins the center of a circle with any point on its circumference. (yes i looked it up)

Answer 15

no no I mean what is length of radius in bigger circle?

Answer 16

3.5

Answer 17

Radius is 1/2 the diameter, right?

Answer 18

So to find radius, you just divide diameter by 2

Answer 19

yes

Answer 20

So 12.5/2 = ?

Answer 21

6.25

Answer 22

Yeah, so now find area:

\(A = \pi(6.25)^2\)

Answer 23

39.25 i got kind confused on this part

Answer 24

What are you confused with?

Answer 25

just that whole part with the a= π(6.25.....etc thing

Answer 26

\(\pi\) is pi. You can use 3.14 for that.

\(etc~^2\) mean you multiply "etc" by itself
For example \(4^2 = 4\times4\)

Answer 27

Does that make sense?

Answer 28

yes

Answer 29

OK so \(A = \pi(6.25)^2\)

First, multiply 6.25 by itself

Answer 30

Then multiply it by 3.14

Answer 31

i got 122.6525

Answer 32

Good enough.

This is area of bigger circle. Keep that in mind.

Now do it again, but with smaller circle (with diameter 3.5).

Can you find area of smaller circle?

Answer 33

so replace 6.25 with 3.5

Answer 34

yeah basically.

Answer 35

kk

Answer 36

i got 38.465

Answer 37

oops forgot to convert diameter into radius

Answer 38

3.5 is diameter, so what is radius?

Answer 39

um 12.5 ?

Answer 40

No. To get radius, you divide diameter by 2.

Answer 41

So 3.5/2 = ?

Answer 42

oh 6.25

Answer 43

I dont see it as the answer ;-; i think I did something wrong

Answer 44

3.5/2 = ?

Answer 45

1.75

Answer 46

oh wow the online calculator was way off

Answer 47

Yeah. so radius is 1.75.

Now find area of circle.

Answer 48

with radius 1.75

Answer 49

1.75 x ? = ( 12.5 ) ?

Answer 50

No. \(A = \pi(1.75)^2\)

Answer 51

oh

Answer 52

9.61625

Answer 53

@geerky42

Answer 54

i guess is didn't do it right. but i double checked and it still was this answer. HELP ;-;

Answer 55

still unsure about this can you help @10115658

Answer 56

find the area of the larg circle and the small circle

Answer 57

12.5 is the area i belive

Answer 58

no, that is the diameter

Answer 59

remember, the area of a circle is
\[\pi r ^{2}\]

Answer 60

radius is half the diameter

Answer 61

6.25

Answer 62

yep, now plug it into the formula

Answer 63

3.14 x 6.25 ?

Answer 64

19.625

Answer 65

6.25^2

Answer 66

39.0625 ?

Answer 67

don't forget about the pi

Answer 68

122.65625

Answer 69

yep, now find the area of the smaller circle

Answer 70

um

Answer 71

okay, so the smaller circle is 3.5

Answer 72

so 3.14 a^2 ?

Answer 73

3.5 is the diameter, what is the radius?

Answer 74

6.25

Answer 75

no its half the diameter

Answer 76

3.125

Answer 77

no what is the diameter of the smaller circle?

Answer 78

3.5?

Answer 79

yes, and the radius is half of that

Answer 80

1.75

Answer 81

now use the formula

Answer 82

9.61625

Answer 83

correct

Answer 84

now subtract the area of the small circle from the large circle

Answer 85

113.03625

Answer 86

good job

Answer 87

so, b

Answer 88

:D yay! thank you for helping me!

Answer 89

np