Question

A circular camera lens has an area of about 19(PIE SIGN) square millimeters. What is the diameter of the camera lens?

Answer 1

Help please

Answer 2

helllp

Answer 3

Hi :)
You know how to get the circumference of a circle when given its diameter?

Answer 4

Or, sorry, the area of a circle, given its diameter.

Answer 5

no

Answer 6

Well, when you have a diameter, how do you get the radius?

Answer 7

?

Answer 8

I forgot these things cuz my class was thought advanced things

Answer 9

Well, the way to get an area of a circle, given its diameter, first you get the radius of the circle, which is just half the diameter \(\large r=\frac12\times d\).

Then the area of a circle is pi times the radius, times the radius (again)
\[\Large A=\pi \times r\times r\]

Answer 10

how do you get the diameter of a circle with a GIVEN area

Answer 11

Just reverse the process ^.^

Answer 12

what do you mean?!

Answer 13

I mean...
\[\Large A=\pi r^2\], put the area in, and then solve for r ^.^

Answer 14

but how can I get the radius if I don't have the diameter!!!

Answer 15

You can also get the radius from the area, silly :)
Using THAT formula \(\huge A=\pi r^2\)

Answer 16

? I don't understand :\

Answer 17

What is A?

Answer 18

A=59.69

Answer 19

Oh, don't put it like that, I suggest you leave it as \(\large 19\pi\) for now :)

Answer 20

ok. so A=\[19\]

Answer 21

MY BAD..A=19PIE

Answer 22

So..
\[\huge 19\pi=\pi r^2\]
NOW solve for the radius, r.

Answer 23

UHY!I DONT UNDERSAND..I HAVE TO GO NOW..

Answer 24

Okay :)
Bye, and good luck ^.^