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/sci/ - Science & Math


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7287719 No.7287719 [Reply] [Original] [archived.moe]

A = πr^2

I got this wrong. I squared the pi and r2 and divided the r and got A/r = π...

then i multiplied the A by both sides and got

r= Aπ

but I know this ain't right and its frustrating me

can someone do a step by step breakdown please?

>> No.7287724

r^2 = A/pi
r = sqrt(A/pi)
what are you trying to achieve OP?

>> No.7287726

Sure thing, anon:
>kill yourself
>???
>fin

>> No.7287768

>>7287724

Just trying to solve for r broham. its a problem i got wrong out of my math book

>> No.7287772

>>7287726

fine, but I wanna get this problem right first. DO YOU MIND?

>> No.7287817

>>7287768
>>7287772
Your question was answered by the first anon. No need to be mad.

Just curious anon, what is your level of schooling?

>> No.7288075

>>7287719
The formula for the area of a circle in Euclidean geometry is given by
<span class="math">
\pi\cdot r^2
[/spoiler]
What it looks like you did was
<span class="math">
(\pi\cdot r)^2
[/spoiler]
If you can't see the difference between the two, then remember your order of operations.

>> No.7288099

>>7287817
I'm teaching high school geometry right now. This is one of the things in the books the school district assigned us and I have to teach this crap tomorrow. It's stupid and it's not my fault I couldn't get the solution. The books are just different this year and they make everything extremely complicated. Seriously fuck common core.

>> No.7288171

>>7288099
How the hell did you get a math teaching job if you don't know basic math?

>> No.7288195

>>7288099
>>7288171
OP, life story please. I seriously need to know how you got this job.

>> No.7288205

>>7288099
You're teaching math and you can't do 6th grade algebra? You're right, there is a problem with public schooling.

>> No.7288211

>>7288099
you're a math teacher, but can't turn A = πr^2 into r = sqrt(A/π) ?
kill yourself

>> No.7288224

>>7288099
'murican detected

>> No.7288233

>>7288205
>6th grade
b-but I didn't learn algebra until 8th grade...

>> No.7288249

>>7288171
>>7288195
I DO know basic math. As I said, it's the book's problem not mine.

I've been teaching geometry for 12 years now. When I was first hired, they never tested me or anything. They just looked at my credentials and hired me since the last man had retired on pretty short notice. Also I'm a woman if that makes any difference.

It's mostly idiocy that they changed the textbooks at this point. My students have enough trouble trying to figure this stuff out. The books have these exercises called "Time to Prove it" and they're absolutely impossible. Before our classroom had an App for the laptops the school bought which would allow my students to just plug in numbers and find areas or perimeters. Using modern solutions to find the answers to our books' problems was what I taught for the last decade, because it's the 21st century for Christsake.

Now though, there is "How to Prove it" idiocy which no one will actually use in the modern world. There is no App for something stupid like that.

>> No.7288258
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7288258

>>7288249
>Also I'm a woman if that makes any difference.
Well THAT explains it.

Wouldn't it be crazy if one of your students came to /sci/ and found his female math teacher asking forchan 4help, posting mildly rare pepes in the process? I would fucking die if that happened to me.

>> No.7288260

>>7288249
>I DO know basic math. As I said, it's the book's problem not mine.
No, you don't. You don't know how to solve that simple equation.

>rest of the post
Are you trolling? I'm genuinely worried someone like you is teaching kids anything.

>> No.7288264

>>7288249
*"Time to Prove it" not "How to Prove it"
Jesus I'm tired. These exercises are really wearing me thin. I'm headed to an early grave at this point. Thanks a lot Congress.

>> No.7288275

>>7288260
>No, you don't. You don't know how to solve that simple equation.
Are you being deliberately stupid? I'm said multiple times that it's the book's fault NOT mine. The people who put this book together deliberately made it incoherent. If you give me the perimeter or area of a circle, I can show my students how to plug in the data to eQuation Solver and get the value for "r". That's not as simple as it sounds because you need to be computer savvy.

I would never ask my students to "isolate for r" like the book wants us to do. That doesn't make sense. You would never do something like that in the real world, and I believe in teaching skills.

>> No.7288277

What do you do as a teacher? Do you just read from a script?

>> No.7288280

>>7288275
OK, now I'm 100% sure you are trolling.

>> No.7288287

This have to be bullshit

>> No.7288291
File: 40 KB, 525x393, black.jpg [View same] [iqdb] [saucenao] [google] [report]
7288291

>>7288275
Someone delete this fucking troll as fuck thread please.
Damn plebs these days...

>> No.7288294

>>7288280
Oh look at this.
>>7288099
>>7288249
>>7288275
I SAID THREE TIMES THAT IT IS NOT MY DAMN FAULT SO DON'T SAY I DIDN'T. Learn to read idiot, and when you're called out on it stop being so damn stubborn. You are pissing me off.

>> No.7288296

Guys this is obviously a bait thread

>> No.7288298
File: 7 KB, 114x140, 1429211107755.jpg [View same] [iqdb] [saucenao] [google] [report]
7288298

>>7288099
>>7288249
>>7288275

10/10

>> No.7288313

>>7288277
Ha no. My job is twofold.
1. I show teens how technology isn't just something for gaming. It can be meaningfully integrated into their lives.
2. Geometry is very important, because otherwise we wouldn't have houses or rulers or almost anything. My hubby used geometry when he was building our deck last year. Never say math doesn't have applications to the real world.

>> No.7288335

>>7287719
Whatever, you guys are kinda annoying me. This was my first time on this board and it will also be my last. But before I go, I'll say something. You think you're good at math, because you learned some useless tricks. But I'm a teacher and I'm actually good at math because I know HOW to teach it. One of you said I was stupid for being a woman (which doesn't bother me tbh), but I have a woman's intuition for teaching. You all talk big, but you wouldn't have a clue if you were put in front of a board. So hey maybe try walking a mile in my shoes before you insult next time. That's all.

>> No.7288343
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7288343

>this whole thread

>> No.7288344
File: 12 KB, 200x195, cool pepe.jpg [View same] [iqdb] [saucenao] [google] [report]
7288344

>>7287719
>>7288335
9/11
Well memed my friend

>> No.7288354

>>7288099
maybe he meant that he's learning. You know, in some countried teach and learn are the same word.

>> No.7288382
File: 28 KB, 640x784, Isolating the Radius.png [View same] [iqdb] [saucenao] [google] [report]
7288382

I'm the anon who made the crack about you being a woman. I was just kidding around with that. But after seeing the rest of your posts:

>>7288275
>it's the book's fault NOT mine
>That's not as simple as it sounds because you need to be computer savvy
>The people who put this book together deliberately made it incoherent
>>7288335
>but I have a woman's intuition for teaching. You all talk big, but you wouldn't have a clue if you were put in front of a board
I can't decide if I should pity you or your students.

I have had to teach many times, a lot of those being impromptu occasions, and it's not that hard.

You obviously don't like taking responsibility for yourself, because you're just blaming some book again and again.

You obviously learned that /sci/ is one of the worst boards on 4chan, too.

By the way, I solved your stupid problem.

>> No.7288402
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7288402

>>7288382
Stop taking the bait.

/sci/ prides itself on being the "smartest board on 4chan", yet it gobbles up bait and troll threads constantly

Too many autists who cant recognize obvious bait?

>> No.7288417
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7288417

>>7288402
>/sci/ falling for bait threads again and again
Surely this can't be so!

>> No.7288427
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7288427

>>7288417
nice meme picture :^)

mind if i save it?

>> No.7288507

>>7288382
That anon's pulling every trick in the book, from "btw im a grill" to "math is useless in the real world"

Stop wasting your time on such cheap bait

>> No.7288541

>>7288382
You can't have a square root in the denominator.

>> No.7288543

>>7288249
>Also I'm a woman if that makes any difference.
Way too obvious.

>> No.7288562

>>7288541
And why the fuck not?

>> No.7288565

>>7288541
THEN HOW THE FUCK AM I MEANT TO CONSTRUCT A LORENTZ INVARIANT INTEGRATION MEASURE FOR MOMENTUM?

>> No.7288580

this thread is epic as h*ck

>> No.7288671
File: 31 KB, 390x488, 1383492266643.jpg [View same] [iqdb] [saucenao] [google] [report]
7288671

>>7288580
>h*ck
Made me chuckle

>> No.7289946

OP here,

that guy derailed this thread. Only the first two replies were mine.

Anyway, Ive figured it out.

you square both sides, divide by r and you get

r= sq Ar/r

>> No.7289965

>>7288565
For all <span class="math"> x\in\mathbb{R} [/spoiler] such that <span class="math"> x> 0 [/spoiler]
<div class="math"> \frac{1}{\sqrt{x}} = \frac{1}{\sqrt{x}} \cdot \frac{\sqrt{x}}{\sqrt{x}} = \frac{\sqrt{x}}{x}</div>

>> No.7289971

>>7288275
9/10, ya had me going

>> No.7289974

>>7288541
You can, it's just not the standard form.

>> No.7290015 [DELETED] 

>>7288099
>fuck common core.

This is not fucking common core's fault. you're just shit at math and shouldn't be teaching it.

>> No.7290017

>>7289965
You just put a square root in the denominator 3 times.

>> No.7290128

>>7287719
<span class="math">A = \pi r^2[/spoiler]
<span class="math">A = \pi ^2 (r^2)^2[/spoiler]
<span class="math">\frac A r = \frac{\pi ^2 r^4} r \Rightarrow \frac A r = \pi[/spoiler]
<span class="math">\frac A r \cdot A = \pi \cdot A \Rightarrow r = A \pi[/spoiler]

Is this what you did? This does not make any sense. I fail to believe that you're not a troll.

>> No.7290626

>>7290128

no, initially i divided r2 to get it under the A, which I realized was wrong cuz' the order is all messed up.

Why would it be a troll? I didn't realize only Calculus level geniuses were allowed to ask questions here. I'm in fucking Algebra class.

da fuck man

my new solution is to square both first so I get a single r, then divide it over. so that I get an

√A/r = √π

but then what? do I now multiply both sides by √A to get the A to the side of the pi?

>> No.7290724

>>7290626
>square r^2 to get a single r
This can't be real

>> No.7290764

>>7290626
>Calculus level geniuses
kek'd

9/10 troll, it doesn't look so convincing but you really got a lot of people so you get a lot of bonus points for that (and the commitment to the role)

>> No.7290783

if you really are a teacher in the United States, then you and your district are the problem with this country.

if you are teaching a math course, then you should be able to prove at least the more necessary theorems. in my senior year of highschool my friends and i proved euclidean geometry theorems/formulas just for fun.

you should be able to do something as simple as what you posted.

if this is a troll then 8.5/10 made me lose hope in America

>> No.7290787
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7290787

>>7288099
>implying

>> No.7290789

>>7290783
50+ posts and this retard still takes the week old bait

You are the problem with /sci/

>> No.7290869

>>7290724

why not? I can't tell who's trolling here tbh.

how about you tell me how to do it instead of being smarmy prick

>> No.7290871

>>7290783


I'm the OP, I just posted. Whoever wrote the post about being a teacher is not me. Fucker made a mockery of my thread when I just wanted someone to help me figure out that dumbass problem.

Just forget it.

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