anonymous
  • anonymous
*Area of the base equals* a)8 pi square units b)16 pi square units c) 64 pi square units
Geometry
  • Stacey Warren - Expert brainly.com
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SOLVED
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schrodinger
  • schrodinger
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
anonymous
  • anonymous
https://suwannee.owschools.com/media/g_geo_2013/8/group100.gif
anonymous
  • anonymous
@jordanwhitehead
anonymous
  • anonymous
@elic2k15

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anonymous
  • anonymous
@UsukiDoll
anonymous
  • anonymous
@math1234
UsukiDoll
  • UsukiDoll
I'm juggling one question back in forth.. so if I'm slow to reply sorry in advanced. Anyway we are given a cylinder |dw:1435669876398:dw|
anonymous
  • anonymous
It's okay
UsukiDoll
  • UsukiDoll
the formula for area of the base of a cylinder is A = pi(r^2)
anonymous
  • anonymous
Okay. But every time I put it into the calculator it shows: either 39.4384 or 50.24
UsukiDoll
  • UsukiDoll
I know.. we don't calculate the pi part.. leave it as is. so if r = 4 what is r^2?
UsukiDoll
  • UsukiDoll
looking at the choices... I think it doesn't want you to calculate the pi.. it's just finding the r and then squaring it
anonymous
  • anonymous
Well then it's just 16
anonymous
  • anonymous
So it's B?
UsukiDoll
  • UsukiDoll
A=pi(4^2) A=pi(16) =16 pi yeah
anonymous
  • anonymous
Thanks. So would it be about the same thing for this problem?
anonymous
  • anonymous
A cylinder has a volume of 245 pi cubic units and a height of 5 units. The diameter of the cylinder is a) 7 units b) 14 units c) 49 units
UsukiDoll
  • UsukiDoll
I think we need the diameter of the cylinder formula.
UsukiDoll
  • UsukiDoll
yeah we need a different formula for that.
UsukiDoll
  • UsukiDoll
\[\large V = \pi r^2h\]
UsukiDoll
  • UsukiDoll
so given height is 5 units volume is 245 pi cubic units . Looks like we're solve for r and then the diameter is twice the radius (d=2r) .. AHA! We need to find the radius first
anonymous
  • anonymous
Yes
UsukiDoll
  • UsukiDoll
ok let V = 245, and h = 5
anonymous
  • anonymous
V r h = � or 2 =
anonymous
  • anonymous
Well that didn't come out right
anonymous
  • anonymous
:(
UsukiDoll
  • UsukiDoll
\[\large 245 = \pi r^2(5)\]
anonymous
  • anonymous
What's "large"?
UsukiDoll
  • UsukiDoll
that's to make the font large
UsukiDoll
  • UsukiDoll
oh are you trying to use the equation tool? right click show math as -> tex command and it will have this code or text you can copy and paste. And then click on the equation tool and paste.
anonymous
  • anonymous
Oh
UsukiDoll
  • UsukiDoll
so we are solving for r that would mean that r needs to be by itself
UsukiDoll
  • UsukiDoll
our first goal is to have r^2 by itself .. and then afterwards we can take the square root
anonymous
  • anonymous
\[V = \pi r2h\]
anonymous
  • anonymous
r is squared
UsukiDoll
  • UsukiDoll
yeah it should have that ^ that carrot sign
UsukiDoll
  • UsukiDoll
\[\large V = \pi r^2h \]
UsukiDoll
  • UsukiDoll
anyway back to this \[\large 245 = \pi r^2(5) \] we need r^2 by itself so what do we need to do?
UsukiDoll
  • UsukiDoll
should we add both sides? subtract both sides? multiply both sides? or.. divide both sides by 5pi
anonymous
  • anonymous
divide both sides by 5 pi
UsukiDoll
  • UsukiDoll
yes. \[\large \frac{245}{5 \pi} = r^2\]
UsukiDoll
  • UsukiDoll
now we take the square root of both sides
anonymous
  • anonymous
So 49 = ?
anonymous
  • anonymous
Umm
UsukiDoll
  • UsukiDoll
we're not done.. we need to take the square root on both sides
UsukiDoll
  • UsukiDoll
UH OH! I need to refresh my screen is crazy
anonymous
  • anonymous
kk
anonymous
  • anonymous
Go ahead
anonymous
  • anonymous
I neded to digest a little
UsukiDoll
  • UsukiDoll
ok so taking the square root of both sides \[\large \sqrt{ \frac{245}{5 \pi} }= \sqrt{r^2}\] what is the square root of r^2
UsukiDoll
  • UsukiDoll
we need to take the square root of r^2 so we can have r
UsukiDoll
  • UsukiDoll
then once we have our r we can get the diameter. which is d =2r
anonymous
  • anonymous
r=2.5
UsukiDoll
  • UsukiDoll
that's not a choice for answers that would've yielded d = 5.. that's not right
anonymous
  • anonymous
No wait. 5 was the height not the diameter
anonymous
  • anonymous
mY BAD SRY
UsukiDoll
  • UsukiDoll
wait a minute we are solving for r.
UsukiDoll
  • UsukiDoll
we have already plugged in V and h... now we need to take the square root of both sides. We're almost there
anonymous
  • anonymous
I was thinking that the diameter is 7
anonymous
  • anonymous
cus 7 squared is 49
UsukiDoll
  • UsukiDoll
\[\large \sqrt{ \frac{245}{5 \pi} }= \sqrt{r^2} \] becomes ??? what is the square root of r^2
anonymous
  • anonymous
49 times 3.14 = 153.86
anonymous
  • anonymous
Umm
anonymous
  • anonymous
7
UsukiDoll
  • UsukiDoll
once we find r we can find the diameter which is d = 2r
UsukiDoll
  • UsukiDoll
What? ok no substituting we are solving for r we need the square root of r^2 .
UsukiDoll
  • UsukiDoll
I want an r by itself
UsukiDoll
  • UsukiDoll
we have square rooted both sides.. which is correct. Now we just need the square root of r^2 Then we have this \[\[\[\large \sqrt{ \frac{245}{5 \pi} }= r\] \]
UsukiDoll
  • UsukiDoll
now the diameter is d=2r so d = 2( That whole square root)
UsukiDoll
  • UsukiDoll
\[\large \sqrt{r^2} \rightarrow r^{\frac{2}{2}} \rightarrow r^1 \rightarrow r \]
UsukiDoll
  • UsukiDoll
so now our \[d=2(\sqrt{\frac{245}{5 \pi}})\]
UsukiDoll
  • UsukiDoll
so we just need 245 divided by 5 pi... take the square root of that result and multiply by 2
anonymous
  • anonymous
7.9
UsukiDoll
  • UsukiDoll
yes. so our diameter is 7.9 kind of a dangerous number because we can round up to 8
UsukiDoll
  • UsukiDoll
7 units would be the closest to the answer.. though the real answer is 7.9
anonymous
  • anonymous
Okay. Look I'm sorry if I aggravated you. It's been a long couple of weeks and I'm really tired
anonymous
  • anonymous
Thanks for the help. I really appreciate it
UsukiDoll
  • UsukiDoll
it's ok ... I'm also tired.. in fact it's almost 4 in the morning. I need zzz's before my dad get suspicious again.
UsukiDoll
  • UsukiDoll
that's why I had my latex wrong... r to the first power is just r if it was r^0 that would've been 1. But I should always take the advice of never do math while tired.
anonymous
  • anonymous
Yeah I can connect with that
UsukiDoll
  • UsukiDoll
I have to go sleep. night
anonymous
  • anonymous
Really. Wow it's 9:55 AM here
anonymous
  • anonymous
well alright
anonymous
  • anonymous
I live in Florida btw

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