Find all School-related info fast with the new School-Specific MBA Forum

It is currently 23 Apr 2014, 19:27

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

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

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
2 KUDOS received
Manager
Manager
Joined: 07 Feb 2010
Posts: 162
Followers: 1

Kudos [?]: 38 [2] , given: 101

GMAT Tests User
In triangle ABC above, what is the length of side BC? [#permalink] New post 21 Dec 2010, 07:17
2
This post received
KUDOS
00:00
A
B
C
D
E

Difficulty:

  55% (medium)

Question Stats:

51% (02:07) correct 48% (01:20) wrong based on 186 sessions
Attachment:
trig2uc8.png
trig2uc8.png [ 9.64 KiB | Viewed 11730 times ]
In triangle ABC above, what is the length of side BC?

(1) Line segment AD has length 6
(2) x = 36
[Reveal] Spoiler: OA

Last edited by Bunuel on 23 Jan 2012, 02:05, edited 1 time in total.
Edited the question and added the image
11 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 17381
Followers: 2888

Kudos [?]: 18483 [11] , given: 2361

GMAT Tests User CAT Tests
Re: IN TRIANGLE ABC [#permalink] New post 21 Dec 2010, 07:31
11
This post received
KUDOS
Expert's post
Attachment:
trig2uc8.png
trig2uc8.png [ 9.64 KiB | Viewed 13271 times ]
In triangle ABC above, what is the length of side BC?

As <BDC=<BCD then the BD=BC. Also as <ADB=180-2x (exterior angle) and the sum of the angles of a triangle is 180 degrees then in triangle ADB we'll have: x+(180-2x)+<ABD=180 --> <ABD=x. Now, we have that <ABD=x=<DAB so AD=BD --> AD=BD=BC.

Question: BC=?

(1) Line segment AD has length 6 --> AD=BD=BC=6. Sufficient.
(2) x = 36 --> we know only angles which is insufficient to get the length of any line segment.

Answer: A.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Senior Manager
Senior Manager
Joined: 28 Dec 2010
Posts: 337
Location: India
Followers: 1

Kudos [?]: 25 [0], given: 33

Re: IN TRIANGLE ABC [#permalink] New post 26 Feb 2011, 21:07
the one point that puzzles me is how did you get /BAD = x ?
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 17381
Followers: 2888

Kudos [?]: 18483 [1] , given: 2361

GMAT Tests User CAT Tests
Re: IN TRIANGLE ABC [#permalink] New post 26 Feb 2011, 23:52
1
This post received
KUDOS
Expert's post
Senior Manager
Senior Manager
Joined: 28 Dec 2010
Posts: 337
Location: India
Followers: 1

Kudos [?]: 25 [0], given: 33

Re: IN TRIANGLE ABC [#permalink] New post 27 Feb 2011, 16:56
thanks bunuel! this explains everything!
2 KUDOS received
Senior Manager
Senior Manager
Joined: 12 Oct 2011
Posts: 279
Followers: 0

Kudos [?]: 17 [2] , given: 110

Re: Geometry [#permalink] New post 22 Jan 2012, 23:36
2
This post received
KUDOS
The question asks the length of side BC. From the figure, you can see that triangle BDC is an isosceles triangle with BD = BC. Thus, to know the length of BC, it is okay if we know the length of BD.

Statement 1:
To solve such problems, you have to know that in a triangle, the measure of the exterior angle is equal to the sum of the two non-adjacent angles of the triangle.

That is, in the given figure, for triangle ABD, angle BDC is the exterior angle. Thus, BDC = ABD + BAD
That is, 2x = ABD + x. Thus ABD = x.

Now, you can see that triangle ABD is an isosceles triangle in which AD = BD = 6. Thus, BD = BC = 6. SUFFICIENT

Statement 2:
x = 36 does not tell you anything about the length of any side. INSUFFICIENT

Answer: A
_________________

Consider KUDOS if you feel the effort's worth it

Manager
Manager
Joined: 16 Dec 2011
Posts: 50
GMAT Date: 04-23-2012
Followers: 0

Kudos [?]: 0 [0], given: 12

Re: In triangle ABC above, what is the length of side BC? [#permalink] New post 25 Jan 2012, 09:45
yeah its A. Bcoz B can only help us to find angle measure but no way we can fund side measrue from there .

so clearly A
Senior Manager
Senior Manager
Joined: 08 Jun 2010
Posts: 398
Location: United States
Concentration: General Management, Finance
GMAT 1: 680 Q50 V32
Followers: 1

Kudos [?]: 50 [0], given: 13

GMAT Tests User
Re: Triangle Problem [#permalink] New post 20 Mar 2012, 18:09
Using Similar triangles we know that
1) BD = BC (angle BDC = angle BCD)
2) We know angle BDA = 180-2x which means angle ABD = x
3) So, from the second similar triangle we know that angle BAD = angle ABD = x
4) Using similar triangles again; AD = BD
5) Combing 1 and 4; AD = BD = BC.

So, A is sufficient.

We don't really need the angle at all.
Manager
Manager
User avatar
Joined: 28 Jul 2011
Posts: 213
Followers: 0

Kudos [?]: 23 [0], given: 13

Re: In triangle ABC above, what is the length of side BC? [#permalink] New post 04 Apr 2012, 06:01
A

we know BD = BC

(A) AD = 6

angle ADB = 180 - 2x


triangle ADB = (180-2x) + x + angle ABD

180 = 180 - 2x + x + angle ABD
x = angle ABD

therefore AD = BD = BC = 6

(B) x = 36
using this information we can only derive that AD = BD = BC , but we dont know value of side
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 17381
Followers: 2888

Kudos [?]: 18483 [0], given: 2361

GMAT Tests User CAT Tests
Re: In triangle ABC above, what is the length of side BC? [#permalink] New post 22 Aug 2013, 04:13
Expert's post
Intern
Intern
Joined: 18 Jun 2013
Posts: 11
Followers: 0

Kudos [?]: 1 [0], given: 3

Re: In triangle ABC above, what is the length of side BC? [#permalink] New post 23 Jan 2014, 23:59
Bunuel wrote:
Bumping for review and further discussion.


Just a question. Would you have been able to solve for length BC if you were given another length? AB for example?
VP
VP
User avatar
Status: I'm back and not stopping until I hit 760+
Joined: 06 Sep 2013
Posts: 1378
Location: United States
Concentration: Finance, General Management
Schools: Wharton '17
GPA: 3.5
WE: Corporate Finance (Investment Banking)
Followers: 7

Kudos [?]: 88 [0], given: 187

GMAT ToolKit User CAT Tests
Re: In triangle ABC above, what is the length of side BC? [#permalink] New post 23 Apr 2014, 13:31
Why is AD=BD=BC? If AD is opposite to X, BD opposite to X as well and BC opposite to 2x?
Shouldn't BC be larger than both or equal to both TOGETHER?

Thanks for clarifying

Cheers!
J :)
Re: In triangle ABC above, what is the length of side BC?   [#permalink] 23 Apr 2014, 13:31
    Similar topics Author Replies Last post
Similar
Topics:
New posts In triangle ABC above, what is the length of side BC? 1) netcaesar 4 14 Nov 2006, 11:10
New posts In Triangle ABC, what is the length of side BC? 1) Line asaf 6 12 Jul 2007, 18:33
New posts In triangle ABC below, what is the length of side BC? 1, pinal2 4 01 Nov 2007, 09:40
New posts Experts publish their posts in the topic In the triangle above, what is the length of the side BC? LM 5 10 Apr 2010, 03:50
New posts 2 Experts publish their posts in the topic In triangle ABC above, what is the length of side BC? Bunuel 7 03 Mar 2014, 23:20
Display posts from previous: Sort by

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

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.