Question

Which of the following expresses the circumference

of a circle in terms of A, its area?

Answer 1

C=2pir,A=pi r^2
just divide.

Answer 2

ehh

Answer 3

Let me get a pen...

Answer 4

ok, square C

Answer 5

then put the value of r^2 from A=pi r^2 in your squared expression.,

Answer 6

ehh

Answer 7

2pir/pir squared?

Answer 8

how did you do it again?

Answer 9

give your options...

Answer 10

2A,2A sqrt pi, 2pi sqrt A, 2 sqrt pi times A, 2piA

Answer 11

your options has r in it ?

Answer 12

tips?

Answer 13

no

Answer 14

it has sqrt

Answer 15

nice, take square of C

Answer 16

square or square root?

Answer 17

we will take square root afterwards, after we eliminate r, first take square

Answer 18

(2pir) quantity squared?

Answer 19

yup.
find r^2 from A=pi r^2

Answer 20

I got 4pi when I divided 4pi sq. r sq./pir sq.

Answer 21

Is that right?

Answer 22

didn't get u,but
r^2 = A/pi.
C^2 = 4 pi^2 r^2
=4 pi^2 A/pi
got this ?

Answer 23

wait

Answer 24

you also sq. the circumference

Answer 25

so hold up

Answer 26

C sq.=4 pi sq. r sq.?

Answer 27

right?

Answer 28

yup

Answer 29

Where did you get A/pi?

Answer 30

A = pi r^2

Answer 31

did you divided circumference sq. by area?

Answer 32

i found r^2 from A
and put it in C^2

Answer 33

cause I got 4pi when I did that

Answer 34

wait

Answer 35

so you solved for radius sq.?

Answer 36

yup.

Answer 37

k...

Answer 38

ehh

Answer 39

ehh

Answer 40

I am still confused

Answer 41

how did we solve for r squared?

Answer 42

ok. then what are u comfortable with?

Answer 43

I know that we sq. C to get 4pi sq. r sq.

Answer 44

so what next?

Answer 45

A=pi r^2
so whats r^2 from here ?

Answer 46

A/pi?

Answer 47

A/pi= r sq.?

Answer 48

yup, now put that in C sq.

Answer 49

k

Answer 50

4 pi sq. times A/pi?

Answer 51

now cancel 1 pi

Answer 52

4 pi times A?

Answer 53

yes. that is C^2
so what is C ?

Answer 54

2 times sq. pi times A?

Answer 55

2 sqrt pi times A
yup

Answer 56

phew, that problem took a while