November 20, 2018 November 20, 2018 09:00 AM PST 10:00 AM PST The reward for signing up with the registration form and attending the chat is: 6 free examPAL quizzes to practice your new skills after the chat. November 20, 2018 November 20, 2018 06:00 PM EST 07:00 PM EST What people who reach the high 700's do differently? We're going to share insights, tips and strategies from data we collected on over 50,000 students who used examPAL.
Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 08 Mar 2012
Posts: 4

Is triangle ABC an isosceles?
[#permalink]
Show Tags
Updated on: 14 Aug 2013, 01:39
Question Stats:
42% (01:24) correct 58% (01:29) wrong based on 492 sessions
HideShow timer Statistics
Attachment:
Screen Shot 20120508 at 1.05.37 PM.png [ 7.39 KiB  Viewed 11470 times ]
Note: Figure not drawn to scale. Is triangle ABC an isosceles? (1) AB/BC = 2 (2) x≠y
Official Answer and Stats are available only to registered users. Register/ Login.
Originally posted by Ljchen121 on 08 May 2012, 09:06.
Last edited by Bunuel on 14 Aug 2013, 01:39, edited 1 time in total.
Edited the OA.




Math Expert
Joined: 02 Sep 2009
Posts: 50627

Re: Is triangle ABC an isosceles?
[#permalink]
Show Tags
09 May 2012, 01:32
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? The OG says it's E though. Please help. Your reasoning is correct answer should be C, not E. Is triangle ABC an isosceles?Attachment:
Screen Shot 20120508 at 1.05.37 PM.png [ 7.39 KiB  Viewed 11375 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. Answer: C.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
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? Extrahard Quant Tests with Brilliant Analytics




Intern
Joined: 08 Mar 2012
Posts: 4

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? The OG says it's E though. Please help.



Intern
Joined: 01 Mar 2012
Posts: 22
Concentration: Operations, Finance
GPA: 3.3
WE: Engineering (Manufacturing)

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: 149
Location: New Delhi, India

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? The OG says it's E though. Please help. Answer should be E 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: 50627

Re: Is triangle ABC an isosceles?
[#permalink]
Show Tags
21 May 2012, 01:42
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? The OG says it's E though. Please help. Answer should be E 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 =45here 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.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
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? Extrahard Quant Tests with Brilliant Analytics



Senior Manager
Joined: 28 Dec 2010
Posts: 281
Location: India

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.



Intern
Joined: 15 Jul 2012
Posts: 34

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: 50627

Re: Is triangle ABC an isosceles?
[#permalink]
Show Tags
14 Sep 2013, 03:00



Manager
Joined: 01 Feb 2017
Posts: 167

Re: Is triangle ABC an isosceles?
[#permalink]
Show Tags
20 May 2017, 15:47
Hi,
Basis Statement 1 alone: Given ratio of two sides of a triangle AB:BC as 2:1 and Triangle Inequality, how is it possible to create an isoslece triangle?
Please advice.



Math Expert
Joined: 02 Sep 2009
Posts: 50627

Re: Is triangle ABC an isosceles?
[#permalink]
Show Tags
21 May 2017, 01:00



Director
Joined: 12 Nov 2016
Posts: 743
Location: United States
GPA: 2.66

Re: Is triangle ABC an isosceles?
[#permalink]
Show Tags
08 Sep 2017, 00:17
Ljchen121 wrote: Attachment: Screen Shot 20120508 at 1.05.37 PM.png Note: Figure not drawn to scale. Is triangle ABC an isosceles? (1) AB/BC = 2 (2) x≠y St 1 This statement just tells us that angle A = 2Y however we don't know for certain whether this is an isosceles because 2(50) + 50 + x =180 x =30 Or you could have an isosceles 2(45) + 45 +45 =180 But we can't make that decision unless we have more info Insuff St 2 Not necessarily St 1 and St 2 If x cannot equal y then we cannot have an equilateral C



NonHuman User
Joined: 09 Sep 2013
Posts: 8817

Re: Is triangle ABC an isosceles?
[#permalink]
Show Tags
18 Sep 2018, 23:45
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.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: Is triangle ABC an isosceles? &nbs
[#permalink]
18 Sep 2018, 23:45






