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

It is currently 23 Jul 2014, 00:23

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

Are all the angles of triangle ABC smaller than 90 degrees?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
CEO
CEO
User avatar
Joined: 21 Jan 2007
Posts: 2771
Location: New York City
Followers: 6

Kudos [?]: 193 [0], given: 4

GMAT Tests User
Are all the angles of triangle ABC smaller than 90 degrees? [#permalink] New post 20 Dec 2007, 13:14
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

50% (02:07) correct 50% (00:28) wrong based on 7 sessions
Are all the angles of triangle ABC smaller than 90 degrees?

1. AB < BC < AC
2. Angle ABC = 80 degrees


What can we infer from 1 and why is it insuff??
1 KUDOS received
Manager
Manager
avatar
Joined: 26 Feb 2007
Posts: 93
Followers: 1

Kudos [?]: 7 [1] , given: 0

 [#permalink] New post 20 Dec 2007, 14:27
1
This post received
KUDOS
Are all the angles of triangle ABC smaller than 90 degrees?

1. AB < BC <AC> =>Angle ABC> AngleCAB> AngleBCA
but all of them might be less than 90 also or AngleABC might be more than 90 So it is insuffcient
2. Angle ABC = 80 degrees => Doesn't give much option about other angle so insuff


from one and two AngleABC =80>Angle CAB>Angle BCA so all are less than 90 hence both are required to answer hence

Answer is C
Manager
Manager
avatar
Joined: 03 Sep 2006
Posts: 233
Followers: 1

Kudos [?]: 5 [0], given: 0

GMAT Tests User
 [#permalink] New post 20 Dec 2007, 19:40
Answer is C:

I. Insuf: the longest side should be less than the sum of the 2 shortest sides: AC < AC + BC
8 < 6 + 3 --> we have one angle that is >90
8 < 8 + 8 --> All angles = 60
Insuff

II. Insuff, Angle ABC = 80 --> the sum of other 2 angles = 100, so it can be 50 + 50 or 95 + 5

Together: suff
Director
Director
User avatar
Joined: 03 Sep 2006
Posts: 893
Followers: 6

Kudos [?]: 87 [0], given: 33

Re: triangle - sides [#permalink] New post 21 Dec 2007, 20:05
bmwhype2 wrote:
Are all the angles of triangle ABC smaller than 90 degrees?

1. AB < BC < AC
2. Angle ABC = 80 degrees


What can we infer from 1 and why is it insuff??


I think it is a good question, my approach would be to draw the figure according to the given statement.

Then it is clear from statement that one of the angle should be Greater than 90deg.

Just draw the figures and it is clear that in one case Angle can be greater than 90deg, as shown in the first two triangles. Therefore, Statement 1 is insufficient.

From statement 2, if we know one angle is 80deg, then the third triangle is possible.

Did you guys tried by drawing the figure or is there better faster approach for GMAT?

Attachments

untitled.PNG
untitled.PNG [ 5.42 KiB | Viewed 2861 times ]

Senior Manager
Senior Manager
avatar
Joined: 18 Aug 2009
Posts: 333
Followers: 7

Kudos [?]: 155 [0], given: 13

GMAT Tests User
Re: triangle - sides [#permalink] New post 20 Sep 2009, 10:53
study wrote:
Statement 2 is sufficient.

When you draw an 80 deg angle..the other two angles have to be less that 90 deg. If you draw a 90 deg angle and an 80 deg angle, the other two sides will not meet. We don't need statement 1. Try drawing the figure..

This is a problem from m23. I think there is an error in the answer choice C.

Anyone can explain if otherwise? Thanks


Sum of all angles of a triangle = 180 degree. So considering one angle equals to 80 degrees, we can have other two angles as 90 degrees and 10 degrees. It it true that the lines making 10 degree angle will be too long, but finally they will meet at certain point. Also if you are saying that the lines making 80 degree and 90 degree angles with one of the sides of the triangle, will not meet, then these two lines must be parallel (?!?). It is not possible for two parallel lines to make angles of different measures with another line. I will suggest you the same, try drawing the figure...
Manager
Manager
avatar
Joined: 04 Feb 2007
Posts: 87
Followers: 2

Kudos [?]: 48 [0], given: 16

geometry II #8 - OA is incorrect [#permalink] New post 17 Mar 2010, 13:22
Are all the angles of triangle ABC smaller than 90 degrees?

1. AB < BC < AC
2. angle(ABC) = 80

official explanation:
Statement (1) by itself is insufficient.

Statement (2) by itself is insufficient.

Statements (1) and (2) combined are sufficient. S1 and S2 gives that angle(ABC) is the largest angle. Thus, the other two angles are smaller than 80 degrees and the answer to the question is "yes".



in a triangle ABC, if angle(ABC) is the largest angle, then side AB cannot be the largest side since its adjacent to angle(ABC).

I believe the answer should be E and not B for the following reason:

For a triangle ABC,

set angle(ABC) = 80, set angle(ACB) = 90, then angle(BAC) must equal 10 and AB<BC<AC. Therefore the answer to the question is NO.

set angle(ABC)=80, set angle(ACB) = 89, then angle(BAC) must equal 11 and AB<BC<AC. Therefore the answer to the question is YES.

the boundary conditions for the angles based on statements 1 and 2 are:
(from statement 2, angle(ABC) = 80)

0 < angle(BAC) < 50
50 < angle(ACB) < 100

Therefore B is incorrect and the answer should be E.

_________________

If you like my post, a kudos is always appreciated ;)

Intern
Intern
avatar
Joined: 13 Mar 2010
Posts: 3
Followers: 0

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

Re: geometry II #8 - OA is incorrect [#permalink] New post 17 Mar 2010, 20:16
the key is :C
(1) a+ (2) combined are sufficient. angle ABC is 80 and is the largest angle, the other two angles are smaller than 80 degrees.
1 KUDOS received
Senior Manager
Senior Manager
User avatar
Joined: 13 Dec 2009
Posts: 264
Followers: 10

Kudos [?]: 99 [1] , given: 13

GMAT Tests User Reviews Badge
Re: geometry II #8 - OA is incorrect [#permalink] New post 19 Mar 2010, 06:47
1
This post received
KUDOS
If both are combined AC is the largest side, ABC is the largest angle and 80*. hence the other two angle has to be lessthan 80* or 90*.
hence C is the answer

_________________

My debrief: done-and-dusted-730-q49-v40

Manager
Manager
avatar
Joined: 04 Feb 2007
Posts: 87
Followers: 2

Kudos [?]: 48 [0], given: 16

Re: geometry II #8 - OA is incorrect [#permalink] New post 19 Mar 2010, 12:55
woops. Man i read the inequality sign backwards!! haha

disregard my initial message, the answer is indeed C.

_________________

If you like my post, a kudos is always appreciated ;)

Manager
Manager
avatar
Joined: 04 Feb 2007
Posts: 87
Followers: 2

Kudos [?]: 48 [0], given: 16

Re: geometry II #8 - OA is incorrect [#permalink] New post 19 Mar 2010, 12:57
if the inequality read:

AB > BC > AC

then the answer should be E, otherwise it is C.
:lol: :oops: :lol: :oops:

_________________

If you like my post, a kudos is always appreciated ;)

VP
VP
avatar
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 1365
Followers: 10

Kudos [?]: 131 [0], given: 10

GMAT Tests User
Re: triangle - sides [#permalink] New post 16 May 2011, 00:53
AC greatest side for angle = 80

hence C

_________________

Visit -- http://www.sustainable-sphere.com/
Promote Green Business,Sustainable Living and Green Earth !!

SVP
SVP
avatar
Joined: 16 Nov 2010
Posts: 1692
Location: United States (IN)
Concentration: Strategy, Technology
Followers: 30

Kudos [?]: 275 [0], given: 36

GMAT Tests User Premium Member Reviews Badge
Re: triangle - sides [#permalink] New post 16 May 2011, 04:10
(1)

If AB = 3, BC = 4, AC = 5, then we have a right triangle

Insufficient

(2) Angle ABC = 80

But the other angles can be 90 degrees and 10 degrees

Insufficient

(1) + (2) says that AC is the greatest side

=> Angle ABC = 80 is greatest angle

=> Every angle < 90

Sufficient

Answer - C

_________________

Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Manager
Manager
avatar
Status: GMAT in 4 weeks
Joined: 28 Mar 2010
Posts: 186
GPA: 3.89
Followers: 1

Kudos [?]: 34 [0], given: 25

GMAT Tests User
Re: triangle - sides [#permalink] New post 18 May 2011, 10:25
hgp2k wrote:
study wrote:
Statement 2 is sufficient.

When you draw an 80 deg angle..the other two angles have to be less that 90 deg. If you draw a 90 deg angle and an 80 deg angle, the other two sides will not meet. We don't need statement 1. Try drawing the figure..

This is a problem from m23. I think there is an error in the answer choice C.

Anyone can explain if otherwise? Thanks


Sum of all angles of a triangle = 180 degree. So considering one angle equals to 80 degrees, we can have other two angles as 90 degrees and 10 degrees. It it true that the lines making 10 degree angle will be too long, but finally they will meet at certain point. Also if you are saying that the lines making 80 degree and 90 degree angles with one of the sides of the triangle, will not meet, then these two lines must be parallel (?!?). It is not possible for two parallel lines to make angles of different measures with another line. I will suggest you the same, try drawing the figure...


Read explanation given above.. I too though this way but its wrong..
Trick here is not in imagination. Its in understanding the naming conventions

_________________

If you liked my post, please consider a Kudos for me. Thanks!

Senior Manager
Senior Manager
avatar
Joined: 20 Dec 2010
Posts: 258
Schools: UNC Duke Kellogg
Followers: 3

Kudos [?]: 25 [0], given: 4

GMAT Tests User
Re: DS- Triangle and Angles [#permalink] New post 30 Jun 2011, 17:58
Great question!....
Intern
Intern
User avatar
Joined: 03 Mar 2011
Posts: 20
GMAT 1: 620 Q46 V29
WE: Sales (Hospitality and Tourism)
Followers: 0

Kudos [?]: 2 [0], given: 12

Re: DS- Triangle and Angles [#permalink] New post 02 Jul 2011, 04:38
tricky one...thanks sidhu for the explanation.
Re: DS- Triangle and Angles   [#permalink] 02 Jul 2011, 04:38
    Similar topics Author Replies Last post
Similar
Topics:
5 Experts publish their posts in the topic Are all angles of triangle ABC smaller than 90 degrees? GMATPASSION 16 19 Mar 2012, 01:43
Experts publish their posts in the topic Are all angles of triangle ABC smaller than 90 degrees? (1) tarek99 7 13 Nov 2008, 01:13
2 Experts publish their posts in the topic Are all angles of triangle ABC smaller than 90 degrees? aaron22197 3 02 Aug 2008, 18:59
1 Are all angles of triangle ABC smaller than 90 degrees? 1. marcodonzelli 4 02 Mar 2008, 07:55
Are all the angles of Triangle ABC smaller than 90 degrees? bz9 7 21 Feb 2007, 03:43
Display posts from previous: Sort by

Are all the angles of triangle ABC smaller than 90 degrees?

  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®.