Question

The function C(r) = 2pie-r gives the circumference of a circle of a radius 'r'. Find the circumference of a circle with radius 3.5inches. Give the exact value as a multiple of pie and an approximate value, rounded to the nearest hundredth.

Answer 1

this ones too easy

we have
C(r)=2*pi*r
here r=3
C(3)=2*pi*3
=6*pi

Answer 2

now pi=3.14 approximately

Answer 3

@ChristaB You should write your function as \[C(r) = 2\pi r\]

Answer 4

substituting
c(3)=6*3.14
=18.84

Answer 5

did that help?

Answer 6

isn't the 'r' = to 3.5?

Answer 7

oops ...typo ..yes its 3.5

Answer 8

sorry

Answer 9

the answer will be 7*pi=21.98

Answer 10

so it will look like this: 3.5 (\[7 \] + ???

Answer 11

it will be 2*3.5*pi

Answer 12

2*3.5=7

Answer 13

gt it ?

Answer 14

so, punching the numbers into the calculator, using the pi button.. the answer I came up with is 21.9911..... is this correct?

Answer 15

i gt 21.98

Answer 16

Now, to round that to the nearest hundredth.... the answer becomes 22.00???

Answer 17

yepe

Answer 18

gt it?

Answer 19

I think so... my confusion right now though is the rounding to the nearest hundredth... does the 21.99114 rounding to the nearest hundredth become 22.