Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 25 May 2017, 20:16

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# In the triangle above, what is the length of the side BC?

Author Message
TAGS:

### Hide Tags

Director
Joined: 03 Sep 2006
Posts: 875
Followers: 7

Kudos [?]: 893 [0], given: 33

In the triangle above, what is the length of the side BC? [#permalink]

### Show Tags

10 Apr 2010, 04:50
00:00

Difficulty:

(N/A)

Question Stats:

73% (01:45) correct 27% (00:41) wrong based on 32 sessions

### HideShow timer Statistics

Attachment:
File comment: Figure

Triangle.PNG [ 2.67 KiB | Viewed 2224 times ]

In the triangle above, what is the length of the side BC?

(1) Line segment AD has length 6
(2) x= 36

Can someone please explain the logic behind the explanation given in the official guide for the quantitative review-1st edition (question #117).

What I can't understand from the explanation is that it has been assumed that

angle ABD + angle DAB = 2x

will imply that ABD = DAB =x.

Why is the above true? Isn't it possible that ABD = 1.5x and DAB = 0.5x?

Why those two have to be equal?
Math Expert
Joined: 02 Sep 2009
Posts: 38890
Followers: 7735

Kudos [?]: 106153 [0], given: 11607

### Show Tags

10 Apr 2010, 05:30
LM wrote:
Can someone please explain the logic behind the explanation given in the official guide for the quantitative review-1st edition (question #117).

In the triangle above, what is the length of the side BC?

(1) Line segment AD has length 6

(2) x= 36

What I can't understand from the explanation is that it has been assumed that

angle ABD + angle DAB = 2x

will imply that ABD = DAB =x.

Why is the above true? Isn't it possible that ABD = 1.5x and DAB = 0.5x?

Why those two have to be equal?

We can no way assume that ABD=DAB=x, from ABD+DAB=2x. If we knew that either ABD or DAB equals to x, then the answer would be A. But in it's current form the answer should be E.
_________________
Director
Joined: 03 Sep 2006
Posts: 875
Followers: 7

Kudos [?]: 893 [0], given: 33

### Show Tags

10 Apr 2010, 17:28
Bunuel wrote:
LM wrote:
Can someone please explain the logic behind the explanation given in the official guide for the quantitative review-1st edition (question #117).

In the triangle above, what is the length of the side BC?

(1) Line segment AD has length 6

(2) x= 36

What I can't understand from the explanation is that it has been assumed that

angle ABD + angle DAB = 2x

will imply that ABD = DAB =x.

Why is the above true? Isn't it possible that ABD = 1.5x and DAB = 0.5x?

Why those two have to be equal?

We can no way assume that ABD=DAB=x, from ABD+DAB=2x. If we knew that either ABD or DAB equals to x, then the answer would be A. But in it's current form the answer should be E.

This means that the Official Guide has the wrong answer. Official Guide gives the answer as "A", but I thought ( same as you!) that the answer should be"E".
whom shall we inform if the answer in the Official Guide is wrong?
CEO
Joined: 17 Nov 2007
Posts: 3586
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 574

Kudos [?]: 3977 [0], given: 360

### Show Tags

10 Apr 2010, 19:09
In my OG Quant 1 DAB=x.
_________________

HOT! GMAT TOOLKIT 2 (iOS) / GMAT TOOLKIT (Android) - The OFFICIAL GMAT CLUB PREP APP, a must-have app especially if you aim at 700+ | PrepGame

Director
Joined: 03 Sep 2006
Posts: 875
Followers: 7

Kudos [?]: 893 [0], given: 33

### Show Tags

10 Apr 2010, 21:12
walker wrote:
In my OG Quant 1 DAB=x.

Walker,

I checked it again, and I believe they have not published two versions of Quant-I (review).

The official guide, page number 193, shows that BDC = 2x and BCD = 2x.

That's why I thought somehow the explanation or rather the answer given in the OG is incorrect.
Manager
Joined: 05 Mar 2010
Posts: 217
Followers: 1

Kudos [?]: 32 [0], given: 8

### Show Tags

16 Apr 2010, 04:58
I think LM is right
Even in my quant, nothing is mentioned about angle DAB

explanation by OG - let angle DBA be y , so x + y = 2x (exterior angle) so x =y .........(but nowhere they mention that DAB is x)

Can official guide be wrong??? Surprise Surprise
_________________

Success is my Destiny

Re: Quantitative Review #117   [#permalink] 16 Apr 2010, 04:58
Similar topics Replies Last post
Similar
Topics:
3 The lengths of the sides of triangle ABC are such that AB = x + 2, BC 4 02 Mar 2015, 07:24
1 In the figure above, what is the length of segment BC ? 3 26 Dec 2014, 10:09
26 In triangle ABC above, what is the length of side BC? 15 23 Feb 2017, 05:44
44 In triangle ABC above, what is the length of side BC? 24 11 Apr 2017, 07:50
1 In triangle ABC above, what is the lenght of side BC? 1) 8 22 Nov 2010, 13:36
Display posts from previous: Sort by