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

It is currently 25 Oct 2014, 18:01

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

Is the triangle depicted above isosceles?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
avatar
Joined: 10 Jul 2013
Posts: 343
Followers: 3

Kudos [?]: 121 [0], given: 102

Is the triangle depicted above isosceles? [#permalink] New post 21 Aug 2013, 16:53
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

69% (02:28) correct 31% (01:07) wrong based on 95 sessions
Attachment:
isosceles.png
isosceles.png [ 5.04 KiB | Viewed 1104 times ]
Is the triangle depicted above isosceles? (Figure not necessarily drawn to scale.)

(1) 180° − (a + c) = 60°
(2) a = 2b − c
[Reveal] Spoiler: OA

_________________

Asif vai.....


Last edited by Bunuel on 22 Aug 2013, 00:58, edited 1 time in total.
Edited the question.
Intern
Intern
avatar
Joined: 21 Aug 2013
Posts: 6
Followers: 0

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

Re: Is the triangle depicted above isosceles? [#permalink] New post 21 Aug 2013, 19:04
Asifpirlo wrote:
Is the triangle depicted above isosceles?
(Figure not necessarily drawn to scale.)

(1)180° − (a + c) = 60°
(2)a = 2b − c


Both the conditions are not sufficient to answer the question.

1st will give a+c =120
2nd will give a+c =2b

hence b=60
which does not tell whether triangle is isosceles or not.
Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23422
Followers: 3618

Kudos [?]: 28976 [1] , given: 2874

Re: Is the triangle depicted above isosceles? [#permalink] New post 22 Aug 2013, 01:25
1
This post received
KUDOS
Expert's post
Image
Is the triangle depicted above isosceles? (Figure not necessarily drawn to scale.)

According to the OG an isosceles triangle has at least two sides of the same length.

a + b + c =180°

(1) 180° − (a + c) = 60° --> a + c =120° --> b = 60°. Now, if a = b = c = 60°, then the triangle is isosceles (equilateral) but if a = 100°, b = 60° and c = 20°, then the triangle is NOT isosceles. Not sufficient.

(2) a = 2b − c --> a + c =2b --> 2b + b = 180° --> b = 60°. The same as above. Not sufficient.

(1)+(2) Both statements provide with the same infor. Not sufficient.

Answer: E.

Notice that if we define an isosceles triangle as a triangle with exactly two equal sides (not the case for the GMAT) then the answer will be D.
_________________

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

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
avatar
Joined: 11 Jul 2012
Posts: 52
GMAT 1: 650 Q49 V29
Followers: 0

Kudos [?]: 6 [0], given: 20

Re: Is the triangle depicted above isosceles? [#permalink] New post 25 Aug 2013, 05:08
Bunuel wrote:
Image
Is the triangle depicted above isosceles? (Figure not necessarily drawn to scale.)

According to the OG an isosceles triangle has at least two sides of the same length.

a + b + c =180°

(1) 180° − (a + c) = 60° --> a + c =120° --> b = 60°. Now, if a = b = c = 60°, then the triangle is isosceles (equilateral) but if a = 100°, b = 60° and c = 20°, then the triangle is NOT isosceles. Not sufficient.

(2) a = 2b − c --> a + c =2b --> 2b + b = 180° --> b = 60°. The same as above. Not sufficient.

(1)+(2) Both statements provide with the same infor. Not sufficient.

Answer: E.

Notice that if we define an isosceles triangle as a triangle with exactly two equal sides (not the case for the GMAT) then the answer will be D.



Why would the answer be D in that case Bunuel? None of the statements would be able to tell us the exact values for C or A. we would just know their sum to be 180....please point out the problem in my assumptions....
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23422
Followers: 3618

Kudos [?]: 28976 [0], given: 2874

Re: Is the triangle depicted above isosceles? [#permalink] New post 25 Aug 2013, 05:13
Expert's post
avaneeshvyas wrote:
Bunuel wrote:
Image
Is the triangle depicted above isosceles? (Figure not necessarily drawn to scale.)

According to the OG an isosceles triangle has at least two sides of the same length.

a + b + c =180°

(1) 180° − (a + c) = 60° --> a + c =120° --> b = 60°. Now, if a = b = c = 60°, then the triangle is isosceles (equilateral) but if a = 100°, b = 60° and c = 20°, then the triangle is NOT isosceles. Not sufficient.

(2) a = 2b − c --> a + c =2b --> 2b + b = 180° --> b = 60°. The same as above. Not sufficient.

(1)+(2) Both statements provide with the same infor. Not sufficient.

Answer: E.

Notice that if we define an isosceles triangle as a triangle with exactly two equal sides (not the case for the GMAT) then the answer will be D.



Why would the answer be D in that case Bunuel? None of the statements would be able to tell us the exact values for C or A. we would just know their sum to be 180....please point out the problem in my assumptions....


Ask yourself: do we need the angles to answer YES or NO to the question.
_________________

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

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
avatar
Joined: 11 Jul 2012
Posts: 52
GMAT 1: 650 Q49 V29
Followers: 0

Kudos [?]: 6 [0], given: 20

Re: Is the triangle depicted above isosceles? [#permalink] New post 25 Aug 2013, 10:21
Bunuel wrote:
avaneeshvyas wrote:
Bunuel wrote:
Image
Is the triangle depicted above isosceles? (Figure not necessarily drawn to scale.)

According to the OG an isosceles triangle has at least two sides of the same length.

a + b + c =180°

(1) 180° − (a + c) = 60° --> a + c =120° --> b = 60°. Now, if a = b = c = 60°, then the triangle is isosceles (equilateral) but if a = 100°, b = 60° and c = 20°, then the triangle is NOT isosceles. Not sufficient.

(2) a = 2b − c --> a + c =2b --> 2b + b = 180° --> b = 60°. The same as above. Not sufficient.

(1)+(2) Both statements provide with the same infor. Not sufficient.

Answer: E.

Notice that if we define an isosceles triangle as a triangle with exactly two equal sides (not the case for the GMAT) then the answer will be D.



Why would the answer be D in that case Bunuel? None of the statements would be able to tell us the exact values for C or A. we would just know their sum to be 180....please point out the problem in my assumptions....


Ask yourself: do we need the angles to answer YES or NO to the question.


I am sorry but I seem to miss something here.....to identify a triangle as an isosceles one, we either need to prove two sides equal or the opposite angles equal.....if yes then we do need the measure of individual angles
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23422
Followers: 3618

Kudos [?]: 28976 [0], given: 2874

Re: Is the triangle depicted above isosceles? [#permalink] New post 25 Aug 2013, 10:25
Expert's post
Bunuel wrote:
avaneeshvyas wrote:
Bunuel wrote:
Image
Is the triangle depicted above isosceles? (Figure not necessarily drawn to scale.)

According to the OG an isosceles triangle has at least two sides of the same length.

a + b + c =180°

(1) 180° − (a + c) = 60° --> a + c =120° --> b = 60°. Now, if a = b = c = 60°, then the triangle is isosceles (equilateral) but if a = 100°, b = 60° and c = 20°, then the triangle is NOT isosceles. Not sufficient.

(2) a = 2b − c --> a + c =2b --> 2b + b = 180° --> b = 60°. The same as above. Not sufficient.

(1)+(2) Both statements provide with the same infor. Not sufficient.

Answer: E.

Notice that if we define an isosceles triangle as a triangle with exactly two equal sides (not the case for the GMAT) then the answer will be D.



Why would the answer be D in that case Bunuel? None of the statements would be able to tell us the exact values for C or A. we would just know their sum to be 180....please point out the problem in my assumptions....

Ask yourself: do we need the angles to answer YES or NO to the question.


I am sorry but I seem to miss something here.....to identify a triangle as an isosceles one, we either need to prove two sides equal or the opposite angles equal.....if yes then we do need the measure of individual angles


If we define an isosceles triangle as a triangle with exactly two equal sides (not the case for the GMAT) then the answer will be D, because from a + c =120° (b = 60°) we cannot have only two angles equal to each other, so the answer is NO the triangle is NOT isosceles.
_________________

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

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
avatar
Joined: 23 May 2013
Posts: 53
Concentration: Finance, Social Entrepreneurship
GMAT Date: 11-25-2013
Followers: 0

Kudos [?]: 13 [0], given: 17

Re: Is the triangle depicted above isosceles? [#permalink] New post 09 May 2014, 11:30
Bunuel wrote:

If we define an isosceles triangle as a triangle with exactly two equal sides (not the case for the GMAT) then the answer will be D, because from a + c =120° (b = 60°) we cannot have only two angles equal to each other, so the answer is NO the triangle is NOT isosceles.



Right: The possibilities are either that 1) all the angles are 60 degrees, in which case the triangle is equilateral (which, according to the GMAT is also isosceles), or 2) all the angles are different, which is definitely not isosceles. With the GMAT definition, the OA should be E, but if we use the definition that isosceles triangles have EXACTLY TWO congruent sides, then either answer is sufficient to say NO.
Re: Is the triangle depicted above isosceles?   [#permalink] 09 May 2014, 11:30
    Similar topics Author Replies Last post
Similar
Topics:
14 Experts publish their posts in the topic In the figure above triangles ABC and MNP are both isosceles rxs0005 8 14 Feb 2012, 06:59
isosceles triangle Safiya 3 04 Jun 2009, 09:13
1 isosceles triangle Safiya 6 04 Jun 2009, 09:13
Isosceles Triangle Skewed 5 27 Nov 2007, 14:43
In the isosceles triangle AGF above, |BD|=|DE|=|EF|. In kevincan 3 30 Aug 2006, 15:12
Display posts from previous: Sort by

Is the triangle depicted above isosceles?

  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®.