# CIRCLE HELP!!!

#### MAliCiOuSViCiOuz

##### New member
THE DIAMETER OF A CIRCLE IS 16 KILOMETERS. FIND THE AREA OF THE CIRCLE.

HOW DO YOU FIND THAT OUT?? PLEASE HELP ME! THANK YOU! I HAVE BEEN STRUGGLING WITH THIS PROBLEM!
[/list][/code][/quote]

#### stapel

##### Super Moderator
Staff member
Recall that the radius r is half of the diameter, and plug the radius into the area formula they gave you: "A = (pi)(r<sup>2</sup>)".

Eliz.

#### dark-kitsune

##### New member
Right!!! As stapel said.

So,...
16/2=8.

8 x 3.1428 will equal the area of the circle.

figure it ouT!!!

#### dark-kitsune

##### New member
and square it .sorry!

#### dark-kitsune

##### New member
sory. what i meant ro say was, 8 times 3.1428 and then square the total. got it?? my bad. sory if i confused u

#### tkhunny

##### Moderator
Staff member
Wow, I'm confused.

Let's see, Area of a Circle = [pi]*r<sup>2</sup>

Diameter = 16 km
Radius = Diameter/2 = 16 km / 2 = 8 km <== Notice the units.

Area = [pi]*(8 km)<sup>2</sup> = [pi]*64 km<sup>2</sup> <== Notice the units.

If you need a decimal value, let your calculator tell you what [pi] is. I get about 201.062 km<sup>2</sup>

P.S. Did you notice the units?

#### dark-kitsune

##### New member
So then,

16/2=8

8<sup>2</sup>=64

then (pi)(64)= 201.06 rounded to the nearest tenth.

#### dark-kitsune

##### New member
im right, right? :?: :?

#### Gene

##### Senior Member
Dai jobu desu. Despite all the help.
----------------
Gene

#### dark-kitsune

##### New member
what the heck does that mean???
:?:

#### Gene

##### Senior Member
It means your screen name fooled me and you are right.
-----------------
Gene

oh.

#### tkhunny

##### Moderator
Staff member
dark-kittsune said:
(pi)(64)= 201.06 rounded to the nearest tenth.
Still, no.

1) Where are your units?
2) "nearest tenth"? Better count that again.

Who posted this problem, anyway?

#### Denis

##### Senior Member
My head is sadly shaking to the tune of "boy oh boy"...