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ruben
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Post subject: In the given figure, if the area of the triangle on the  Posted: Sun Aug 26, 2007 3:19 pm |
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gmat prep qn
[img]
in the given figure, if the area of the triangle on the right is twice the area of the triangle on the left, then in terms of s, S=
sq rt 2/2 s
sq rt 3/2 s
sq rt 2 s
sq rt 3 s
2s
[url=http://upload2.postimage.org/458724/photo_hosting.html][img]http://upload2.postimage.org/458724/untitled.jpg[/img][/url]
[/img][/list]
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StaceyKoprince
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Post subject: Posted: Tue Oct 23, 2007 12:37 am |
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| ManhattanGMAT Staff |
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Posts: 6077
Location: San Francisco
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Hi - if you do want us to answer this, please be sure to post an image file that works. :)
_________________
Stacey Koprince
Instructor
Director of Online Community
ManhattanGMAT
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Guest
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Post subject: Posted: Mon Sep 22, 2008 10:44 pm |
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hi! i am stuck with this question as well but don't know how to post images :=( i cannot do any copying once i am in GMATPrep program. It doesn't even let me right click. can someone tell me how to do it? then i will post the figure for this problem.
thanks so much.
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StaceyKoprince
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Post subject: Posted: Wed Oct 15, 2008 1:05 am |
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| ManhattanGMAT Staff |
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Posts: 6077
Location: San Francisco
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I don't know how to either! I've never posted an image! Can someone help our guest out?
_________________
Stacey Koprince
Instructor
Director of Online Community
ManhattanGMAT
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Priyanka
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Post subject: Posted: Thu Oct 16, 2008 12:47 pm |
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Hi
You just have to do a print screen of the image. i.e. go to the GMATPrep Screen and on your keyboard press the Print Scr button, and then paste the given image in paint and save it as a .gif or .jpeg and voila u have ur image!!!
Hope it helps :)
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Guest
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Post subject: Posted: Thu Oct 16, 2008 7:57 pm |
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I hope this can help..
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Guest
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Post subject: Similar triangles Posted: Thu Oct 23, 2008 6:25 am |
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Hi
It is clear that these are similar triangles - therefore their sides are proportionate/ of the same proportion
We know that the area of the bigger triangle is twice the are of the smaller one
Let us assume that S =4 and H =4 - the area of the bigger triangle is therefore S*H/2 =16/2 = 8
Therefore twice the area of the smaller triangle is 2(sh/2) =8 , sh =8
Since S=H, s=h and therefore 2s=8, s=2(2)^1/2
Therefore S/s= 4/2 SQRT 2 or
S =4s/2 sqrt 2 or sqrt 2 s
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RonPurewal
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Post subject: Posted: Fri Nov 07, 2008 5:51 am |
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| ManhattanGMAT Staff |
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here's a nice takeaway for problems like this one.
in SIMILAR FIGURES, the RATIO OF AREAS is (RATIO OF LENGTHS)^2.
as long as we're at it:
in SIMILAR SOLIDS, the RATIO OF VOLUMES is (RATIO OF LENGTHS)^3.
in SIMILAR SOLIDS, the RATIO OF SURFACE AREAS is (RATIO OF LENGTHS)^2.
or, if you prefer your variables raw,
in similar figures:
length ratio = a : b
area ratio = a^2 : b^2
in similar 3-d solids:
length ratio = a : b
surface area ratio = a^2 : b^2
volume ratio = a^3 : b^3
in this problem, you have a^2 : b^2 = 2 : 1. if you know the result(s) above, then it follows at once that a : b (the ratio of lengths, which is what you're looking for) is √2 : 1.
good times!
notice that even if you're CLUELESS on this problem, you can still easily eliminate choices (a) and (b), each of which implies that the big "S" is actually smaller than the small "s". that is ridiculous.
this deduction follows from the fact that both √2/2 and √3/2 are less than 1. you should all know √2 ≈ 1.4 or 3/2, and √3 ≈ 1.7 or 7/4, so you should be able to figure this out.
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ericaliu123
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Post subject: Re: In the given figure, if the area of the triangle on the Posted: Thu Nov 10, 2011 9:06 pm |
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Quote: Since S=H, s=h and therefore 2s=8, s=2(2)^1/2
Therefore S/s= 4/2 SQRT 2 or
S =4s/2 sqrt 2 or sqrt 2 s Hi, how do you get from 2s=8 to s==2(2)^1/2? Please advise. Thank you.
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RonPurewal
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Post subject: Re: In the given figure, if the area of the triangle on the Posted: Wed Nov 23, 2011 6:19 am |
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| ManhattanGMAT Staff |
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ericaliu123 wrote: how do you get from 2s=8 to s==2(2)^1/2? Please advise.
Thank you. this poster apparently wrote 2s when he/she should have written s^2. so, that mysterious expression is just the simplified form of √8 = 2√2.
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