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# The shaded area is what percentage of the area of the

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Current Student
Joined: 12 Jun 2008
Posts: 287
Schools: INSEAD Class of July '10

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04 Jul 2008, 16:05

Actually it is not BC = 2r/cos(37°) but BC = 4r/cos(37°). Same thing BD = 4r/sin(37°)

(hence the factor 4 difference: I wrote radius for diameter...)

Then the area of the parallelogram is BD*BC = 16*r^2/(cos(37°)*sin(37°))

The ratio we want is then $$\frac{(4-\Pi)cos(37^o)sin(37^o)}{16}$$ (exact answer, no approximation of any kind)

Senior Manager
Joined: 12 Apr 2008
Posts: 499
Location: Eastern Europe
Schools: Oxford

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04 Jul 2008, 16:11
Hi, jallenmorris,

The last version of the pic., again, does not give sufficient info:
you can change the angle BAD, and obtain different values of parallelogram’s area.

The fact that in your picture B is strictly above D does not help: it could be merely a coincidence. So in the end the picture doesn’t let us to correctly infer that ABD is right triangle. On real GMAT pictures, all measures that intended to be fixed, are explicitly fixed.

So I think this would be somewhat more proper picture:

Attachment:

GMATQuestionBestPicture_edit.gif [ 6.48 KiB | Viewed 511 times ]

Also, you need to state that ABCD is parallelogram.
SVP
Joined: 30 Apr 2008
Posts: 1874
Location: Oklahoma City
Schools: Hard Knocks

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04 Jul 2008, 20:03
If you read the first post, I do state it's a parallelogram by stating AD || BC and AB || DC.

Attachment:

GmatQuestion_v_3.14.gif [ 6.8 KiB | Viewed 497 times ]

greenoak wrote:
Hi, jallenmorris,

The last version of the pic., again, does not give sufficient info:
you can change the angle BAD, and obtain different values of parallelogram’s area.

The fact that in your picture B is strictly above D does not help: it could be merely a coincidence. So in the end the picture doesn’t let us to correctly infer that ABD is right triangle. On real GMAT pictures, all measures that intended to be fixed, are explicitly fixed.

So I think this would be somewhat more proper picture:

Attachment:
The attachment GMATQuestionBestPicture_edit.gif is no longer available

Also, you need to state that ABCD is parallelogram.

_________________

------------------------------------
J Allen Morris
**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$. GMAT Club Premium Membership - big benefits and savings Current Student Joined: 12 Jun 2008 Posts: 287 Schools: INSEAD Class of July '10 Re: Geometry Proportions [#permalink] ### Show Tags 06 Jul 2008, 02:19 Oski wrote: I think it is me who made made a mistake Question for you english speakers: Is this correct? Do you say "it is me who made made a mistake" or do you say "it is I who made made a mistake"? Thanks! SVP Joined: 30 Apr 2008 Posts: 1874 Location: Oklahoma City Schools: Hard Knocks Re: Geometry Proportions [#permalink] ### Show Tags 06 Jul 2008, 07:35 I believe this is the correct format: "It is I who made a mistake." - Use I and only 1 "made". _________________ ------------------------------------ J Allen Morris **I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$.

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Current Student
Joined: 12 Jun 2008
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06 Jul 2008, 07:50
jallenmorris wrote:
I believe this is the correct format:

"It is I who made a mistake." - Use I and only 1 "made".

SVP
Joined: 30 Apr 2008
Posts: 1874
Location: Oklahoma City
Schools: Hard Knocks

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06 Jul 2008, 07:54
also, realize this....even though the proper form is "It is I who made a mistake." I doubt many native english speakers actually say this. Most people are going to say "It was me that made the mistake." or they'll use any other form of saying it is their fault.
_________________

------------------------------------
J Allen Morris
**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a.

GMAT Club Premium Membership - big benefits and savings

Current Student
Joined: 12 Jun 2008
Posts: 287
Schools: INSEAD Class of July '10

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06 Jul 2008, 07:59
jallenmorris wrote:
also, realize this....even though the proper form is "It is I who made a mistake." I doubt many native english speakers actually say this. Most people are going to say "It was me that made the mistake." or they'll use any other form of saying it is their fault.

"It is I who made a mistake" but "It is me that made a mistake"... No wonders I have difficulties with the sentence correction questions...

But thanks for your patience with this !
Re: Geometry Proportions   [#permalink] 06 Jul 2008, 07:59

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