Is triangle ABC an isosceles? : GMAT Data Sufficiency (DS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 23 Jan 2017, 23:22

### 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

# Is triangle ABC an isosceles?

Author Message
TAGS:

### Hide Tags

Intern
Joined: 08 Mar 2012
Posts: 4
Schools: CBS '19 (S)
Followers: 0

Kudos [?]: 7 [0], given: 0

Is triangle ABC an isosceles? [#permalink]

### Show Tags

08 May 2012, 09:06
3
This post was
BOOKMARKED
00:00

Difficulty:

85% (hard)

Question Stats:

38% (01:54) correct 62% (00:52) wrong based on 274 sessions

### HideShow timer Statistics

Attachment:

Screen Shot 2012-05-08 at 1.05.37 PM.png [ 7.39 KiB | Viewed 6508 times ]
Note: Figure not drawn to scale.
Is triangle ABC an isosceles?

(1) AB/BC = 2

(2) x≠y
[Reveal] Spoiler: OA

Last edited by Bunuel on 14 Aug 2013, 01:39, edited 1 time in total.
Edited the OA.
Intern
Joined: 08 Mar 2012
Posts: 4
Schools: CBS '19 (S)
Followers: 0

Kudos [?]: 7 [0], given: 0

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

08 May 2012, 09:11
I thought it was C, because the only way for the triangle to be isosceles given both conditions is for BC = AC , and that's not possible because side AC + BC (assuming they are the same length) would equal AB. And the third side of the triangle must be greater than the sum of the other two sides or less than the difference of the other two sides. So given both conditions, should we be able to say for sure that the triangle is not isosceles?

Math Expert
Joined: 02 Sep 2009
Posts: 36618
Followers: 7103

Kudos [?]: 93597 [8] , given: 10579

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

09 May 2012, 01:32
8
KUDOS
Expert's post
Ljchen121 wrote:
I thought it was C, because the only way for the triangle to be isosceles given both conditions is for BC = AC , and that's not possible because side AC + BC (assuming they are the same length) would equal AB. And the third side of the triangle must be greater than the sum of the other two sides or less than the difference of the other two sides. So given both conditions, should we be able to say for sure that the triangle is not isosceles?

Is triangle ABC an isosceles?
Attachment:

Screen Shot 2012-05-08 at 1.05.37 PM.png [ 7.39 KiB | Viewed 6429 times ]

(1) AB/BC = 2 --> $$AB\neq{BC}$$. Not sufficient on its own.
(2) x≠y --> $$AB\neq{AC}$$. Not sufficient on its own.

(1)+(2) Since $$AB\neq{BC}$$ and $$AB\neq{AC}$$, then the only way ABC to be isosceles is when $$AC=BC$$. But in this case as given that AB=2BC then AB=BC+BC=BC+AC which is not possible because the length of any side of a triangle must be smaller than the sum of the other two sides. So, $$AC\neq{BC}$$, which means that ABC is not isosceles. Sufficient.

_________________
Senior Manager
Affiliations: UWC
Joined: 09 May 2012
Posts: 399
GMAT 1: 620 Q42 V33
GMAT 2: 680 Q44 V38
GPA: 3.43
WE: Engineering (Entertainment and Sports)
Followers: 28

Kudos [?]: 1112 [0], given: 100

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

09 May 2012, 20:45
E

Both statements give you an impossible triangle
Intern
Joined: 01 Mar 2012
Posts: 32
Concentration: Operations, Finance
GMAT 1: 740 Q49 V41
GPA: 3.3
WE: Engineering (Manufacturing)
Followers: 1

Kudos [?]: 4 [0], given: 46

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

16 May 2012, 04:27
Initially tricked upon thinking it is E. Thanks Bunuel for the explanation.
Manager
Affiliations: Project Management Professional (PMP)
Joined: 30 Jun 2011
Posts: 213
Location: New Delhi, India
Followers: 5

Kudos [?]: 67 [0], given: 12

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

21 May 2012, 01:35
Ljchen121 wrote:
I thought it was C, because the only way for the triangle to be isosceles given both conditions is for BC = AC , and that's not possible because side AC + BC (assuming they are the same length) would equal AB. And the third side of the triangle must be greater than the sum of the other two sides or less than the difference of the other two sides. So given both conditions, should we be able to say for sure that the triangle is not isosceles?

even if we cosider both 1) & 2) consider the below examples:

Case 1--> x= 30, y=100 & third angle= 50
Case 2--> x=45, y=90 & third angle =45

here both 1) & 2) are satisfied but there is contradiction in result, i.e. in one case traingle is issoceles, in other it is not, for the same conditions. Hence E
_________________

Best
Vaibhav

If you found my contribution helpful, please click the +1 Kudos button on the left, Thanks

Math Expert
Joined: 02 Sep 2009
Posts: 36618
Followers: 7103

Kudos [?]: 93597 [2] , given: 10579

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

21 May 2012, 01:42
2
KUDOS
Expert's post
narangvaibhav wrote:
Ljchen121 wrote:
I thought it was C, because the only way for the triangle to be isosceles given both conditions is for BC = AC , and that's not possible because side AC + BC (assuming they are the same length) would equal AB. And the third side of the triangle must be greater than the sum of the other two sides or less than the difference of the other two sides. So given both conditions, should we be able to say for sure that the triangle is not isosceles?

even if we cosider both 1) & 2) consider the below examples:

Case 1--> x= 30, y=100 & third angle= 50
Case 2--> x=45, y=90 & third angle =45

here both 1) & 2) are satisfied but there is contradiction in result, i.e. in one case traingle is issoceles, in other it is not, for the same conditions. Hence E

When considering the statements together the red scenario is not possible. If x=z then it would mean that AC=BC. But in this case as given that AB=2BC then AB=BC+BC=BC+AC which is not possible because the length of any side of a triangle must be smaller than the sum of the other two sides.
_________________
Senior Manager
Joined: 28 Dec 2010
Posts: 334
Location: India
Followers: 1

Kudos [?]: 201 [0], given: 33

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

23 May 2012, 10:51
intense reasoning guys! I picked E and didnt test the problem from the length of sides perspective. looked only at the angles.
Math Expert
Joined: 02 Sep 2009
Posts: 36618
Followers: 7103

Kudos [?]: 93597 [0], given: 10579

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

14 Aug 2013, 01:40
Bumping for review and further discussion.
_________________
Intern
Joined: 15 Jul 2012
Posts: 38
Followers: 0

Kudos [?]: 4 [0], given: 245

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

13 Sep 2013, 11:54
can side AB=AC from 1st statement by making x=y?
Math Expert
Joined: 02 Sep 2009
Posts: 36618
Followers: 7103

Kudos [?]: 93597 [0], given: 10579

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

14 Sep 2013, 03:00
saggii27 wrote:
can side AB=AC from 1st statement by making x=y?

Yes, for (1) it's possible that AB=AC as well as it's possible that AB#AC, so the first statement is not sufficient.
_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13534
Followers: 577

Kudos [?]: 163 [0], given: 0

Re: Is triangle ABC an isosceles? [#permalink]

### Show Tags

17 Mar 2016, 10:44
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Is triangle ABC an isosceles?   [#permalink] 17 Mar 2016, 10:44
Similar topics Replies Last post
Similar
Topics:
3 The triangle ABC is isosceles. What is the measure of the angle ACB? ( 3 16 Jul 2015, 00:37
2 Triangle ABC is isosceles. What is the measure of angle BAC? 5 07 Jan 2015, 06:36
2 If triangle ABC is an isosceles triangle 5 05 Nov 2012, 11:37
3 What is the perimeter of the isosceles right triangle ABC 10 12 Jul 2011, 08:46
16 Is triangle ABC isosceles? 9 09 Dec 2010, 06:22
Display posts from previous: Sort by