Question

omg someone help :( tell me how to solve it i wanna learn..thanks
The are of a circle is 18(pi) square inches.What is the circumference of the circle to the nearest inch?
use (pi)=3.14

Answer 1

*area

Answer 2

area = pi * r^2
circumference = 2 * pi * r

r = radius

find your radius first by using the area equation and then you'll be able to find the circumference.

Does that help at all?

Answer 3

ummm..ok so 3.14*r^2 but how would i find the radius with the area equation if i cant do anything else

Answer 4

OHHH i think i got it

Answer 5

you know that your area = 18

18 = 3.14 * r^2

so r is the square root of 18/3.14 ... so far so good?

Answer 6

Awesome!

Answer 7

i thought i had to multiply 18 by pi

Answer 8

To get rid of pi on the right hand side you have to divide by 3.14 so you'll want do the same thing on the right hand side

Answer 9

oh ok

Answer 10

i got 5.73

Answer 11

so that's 18/pi ... now you need \[\sqrt{5.73}\]

because right now it r^2 = 5.73 ... ok?

Answer 12

ok i got 2.39

Answer 13

great ... so now for your circumference

2 * pi * r (which is 2.39)

and don't forget to add inches to your answer :)

Answer 14

ok so i got 15.0092

Answer 15

i can just put 15.92 right?

Answer 16

You can't remove the zeros in between. They're important. :)

Did your teacher tell you to round to any particular decimal place?

Answer 17

oh ok, and no (: thank you so much

Answer 18

Great ... I'd go with 15 inches myself. You are so very welcome! It was my pleasure.