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Triangle, exterior angles.

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Triangle, exterior angles.

by matteomasciotti » Sat Jan 19, 2013 5:36 am
Hello there,
I came across this fairly simple problem on GMAT quantitative review (DS #117)
Which states the following:

In triangle ABC, what is the length of side BC?
1)Line segment AD has length 6
2)x=36

The image attached should provide the useful information

So the book says, that the exterior angle of a triangle is equal to the sum of the interior remote angles.fair enough. but I don't how the book assigns variables to the angles in the way shown in the picture.

Can someone help me out?
Thank you
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by brianlange77 » Sat Jan 19, 2013 9:31 am
matteomasciotti wrote:Hello there,
I came across this fairly simple problem on GMAT quantitative review (DS #117)
Which states the following:

In triangle ABC, what is the length of side BC?
1)Line segment AD has length 6
2)x=36

The image attached should provide the useful information

So the book says, that the exterior angle of a triangle is equal to the sum of the interior remote angles.fair enough. but I don't how the book assigns variables to the angles in the way shown in the picture.

Can someone help me out?
Thank you
Image
Hey there -- good question!

IF you have a few seconds, go and take a look at this thread -- gives you a full explanation to your question below and also highlights the 'trap' that exists in this problem (https://www.manhattangmat.com/forums/qua ... t1708.html).

Let me know if this helps.

Best,

-Brian
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by matteomasciotti » Sat Jan 19, 2013 9:36 am
so ..the problem is a typo? :P
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by brianlange77 » Sat Jan 19, 2013 9:38 am
Do you have the OG 11 version of the book? Typo or not, do you understand the recommendation on how to tackle this particular example?
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by matteomasciotti » Sat Jan 19, 2013 9:46 am
No I have the Quantitative Review 2nd edition. I have the same problem the guy talks about..and the answer seems to be pretty straight. unless you are told that one of those angles in the triangle is called x you are not able to solve it. ..right?
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by brianlange77 » Sat Jan 19, 2013 9:47 am
matteomasciotti wrote:No I have the Quantitative Review 2nd edition. I have the same problem the guy talks about..and the answer seems to be pretty straight. unless you are told that one of those angles in the triangle is called x you are not able to solve it. ..right?
That would seem to make the problem more difficult :-)
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by GMATGuruNY » Sat Jan 19, 2013 1:36 pm
matteomasciotti wrote:No I have the Quantitative Review 2nd edition. I have the same problem the guy talks about..and the answer seems to be pretty straight. unless you are told that one of those angles in the triangle is called x you are not able to solve it. ..right?
Some printings of the OG for Quant omit from the figure that ∠BAD = x.
Check here for a screenshot of the complete question, along with an alternate approach:

https://www.beatthegmat.com/gmatprep-pra ... t1615.html
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My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
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by Brent@GMATPrepNow » Mon Jan 21, 2013 10:09 am
Thought I'd post my solution to the official question (with one angle labeled as x).

Image

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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