Question

The circumference of circle II is 4 feet longer than

the circumference of circle I. How many feet

longer is the radius of circle II than the radius

of circle I?

Answer 1

C = 2pi*r

Answer 2

circumference 4 is 2pir+4

Answer 3

C+4 = 2pi*r+4

Answer 4

the radius is 2pir+4/2pi

Answer 5

so the radius is r+4/2pi

Answer 6

2pir

Answer 7

r/2pi

Answer 8

let us say radius equal 1

Answer 9

2pir = 2pir1 + 4

Answer 10

Solve for r1

Answer 11

Circumference of Circle 2 = C2= 2Pi* R2
C2= 4+ C1
Circumference of circle 1= 2Pi*R1
therfore
4+2piR1=2pi*R2
4=2pi*(r2-r1)
2/pi +r1=r2

Answer 12

1/4 pi?

Answer 13

hmm

Answer 14

let us do this again

Answer 15

so

Answer 16

Circumference 2 equal 2pir+4

Answer 17

radius is 2pir+4/2pi

Answer 18

so radius is r+4

Answer 19

your answer can also be expressed as r2-r1=0.69 (approx)

Answer 20

2pir/2pi=r

Answer 21

I mean

Answer 22

r+2

Answer 23

r+1

Answer 24

ahhh

Answer 25

ahh

Answer 26

so the circles have different radii?

Answer 27

thats the best assumption as these are not Concentric circles

Answer 28

wait

Answer 29

so

Answer 30

circle II is 2pir +4

Answer 31

which is

Answer 32

2(pir+2)?

Answer 33

pir+2

Answer 34

divided by pi

Answer 35

r+2/pi?

Answer 36

circle 2 's circumference = 2pi R2
Circle 1's circumference = 2Pi R1

Answer 37

2pir

Answer 38

pir

Answer 39

r/pi

Answer 40

why do use the same radius R, is it explicitly mentioned ?

Answer 41

no

Answer 42

ahh

Answer 43

ehh

Answer 44

then its better to use different variables for radii of each circle

Answer 45

k

Answer 46

so

Answer 47

does that help, ? then look at the solution I gave

Answer 48

C=2pir1+4

Answer 49

yes thats correct

Answer 50

so

Answer 51

C-4/2pi=r1?

Answer 52

C=2pir2

Answer 53

C/2pi=r2?

Answer 54

lets see circumference equals 4pi

Answer 55

so lets say circle 2 has radii = r2
circle one has radius = r1
circumference of circle 2 is = C2= 4+C1
BUT C2= 2*PI*r2
sub that in the equation
2*pi*r2=4+2*pi*r1
2*pi*(r2-r1)=4
(r2-r1)= 4/(2*pi)
r2-r1=2/pi
r2=r1+2/pi

Answer 56

does that help??

Answer 57

ehh

Answer 58

nvm

Answer 59

I'll take another practice test and see you guys later