GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 27 Jan 2020, 04:29

### 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

# Is the triangle depicted above isosceles?

Author Message
TAGS:

### Hide Tags

Senior Manager
Joined: 10 Jul 2013
Posts: 280
Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

Updated on: 22 Aug 2013, 01:58
1
7
00:00

Difficulty:

35% (medium)

Question Stats:

73% (01:42) correct 27% (01:39) wrong based on 264 sessions

### HideShow timer Statistics

Attachment:

isosceles.png [ 5.04 KiB | Viewed 4113 times ]
Is the triangle depicted above isosceles? (Figure not necessarily drawn to scale.)

(1) 180° − (a + c) = 60°
(2) a = 2b − c

Originally posted by Asifpirlo on 21 Aug 2013, 17:53.
Last edited by Bunuel on 22 Aug 2013, 01:58, edited 1 time in total.
Edited the question.
Math Expert
Joined: 02 Sep 2009
Posts: 60678
Re: Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

22 Aug 2013, 02:25
2

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.

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.
_________________
Intern
Joined: 21 Aug 2013
Posts: 6
Re: Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

21 Aug 2013, 20:04
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.
Intern
Joined: 11 Jul 2012
Posts: 47
GMAT 1: 650 Q49 V29
Re: Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

25 Aug 2013, 06:08
Bunuel wrote:

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.

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....
Math Expert
Joined: 02 Sep 2009
Posts: 60678
Re: Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

25 Aug 2013, 06:13
avaneeshvyas wrote:
Bunuel wrote:

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.

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.
_________________
Intern
Joined: 11 Jul 2012
Posts: 47
GMAT 1: 650 Q49 V29
Re: Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

25 Aug 2013, 11:21
Bunuel wrote:
avaneeshvyas wrote:
Bunuel wrote:

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.

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
Math Expert
Joined: 02 Sep 2009
Posts: 60678
Re: Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

25 Aug 2013, 11:25
Bunuel wrote:
avaneeshvyas wrote:
Bunuel wrote:

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.

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.
_________________
Current Student
Joined: 23 May 2013
Posts: 181
Location: United States
Concentration: Technology, Healthcare
GMAT 1: 760 Q49 V45
GPA: 3.5
Re: Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

09 May 2014, 12:30
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.
Manager
Status: Applied
Joined: 02 May 2014
Posts: 118
Location: India
Concentration: Operations, General Management
GMAT 1: 690 Q47 V38
GPA: 3.35
WE: Information Technology (Computer Software)
Re: Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

19 Mar 2015, 21:09
Both the statements point towards saying that a+ 120 and b=60 hence no knowledge about whether a and b are isosceles.
Non-Human User
Joined: 09 Sep 2013
Posts: 14008
Re: Is the triangle depicted above isosceles?  [#permalink]

### Show Tags

15 Jan 2020, 13:57
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 the triangle depicted above isosceles?   [#permalink] 15 Jan 2020, 13:57
Display posts from previous: Sort by
{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9025000333786011, "perplexity": 1786.6084864099116}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-05/segments/1579251700675.78/warc/CC-MAIN-20200127112805-20200127142805-00071.warc.gz"}