BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

A triangle has three corners

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members
Location: India
Thanked: 267 times
GMAT Score:760

by sanju09 » Mon May 17, 2010 5:15 am
attitude.freak4u wrote:A triangle has three corners A,B and C. A line parallel to BC connects the sides AB and AC. What is the ratio of DE:BC?
1) AD=DB
2) Height of ADE = Height of ABC
This question has just one thing missing and that is the line parallel to BC connects the sides AB and AC in D and E respectively.

This uses the BPT (Basic Proportionality Theorem) in triangles. must revise we all

(1) When AD = DB, the problem reduces from the BPT (Basic Proportionality Theorem) to MPT (Mid Point Theorem) in triangles, and in that case a side of the bigger of the two similar triangles so obtained is twice of the corresponding side of the smaller of the two similar triangles so obtained, and hence, DE:BC = 1:2. Sufficient

(2) Ambiguity starts from here, this is possible only when the bases DE and BC are coinciding, DE:BC = 1:1. Seems sufficient, but it contradicts with (1)

[spoiler]D, if contradiction within the statements could be overlooked by a mass[/spoiler]
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 11
Joined: Wed May 12, 2010 8:30 am
Location: Utah
GMAT Score:710

by KatieB » Mon May 17, 2010 6:44 am
I would say both are sufficient on their own in order to find DE:BC. I'm just starting my studying for the GMAT - and as the earlier poster noted the two conditions would lead to different results for DE:BC - so is that a problem or would the answer still be D - EACH statement ALONE is sufficient?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 537
Joined: Fri Jan 22, 2010 10:06 pmFollowed by: 1 member
Thanked: 14 times

by frank1 » Mon May 17, 2010 7:30 pm
Can a straight line be considered as two parallel lines?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members
Location: India
Thanked: 267 times
GMAT Score:760

by sanju09 » Tue May 18, 2010 12:09 am
frank1 wrote:Can a straight line be considered as two parallel lines?
We can otherwise say that when two or more lines parallel to a line l are each at zero distance from the line l, then these are all coinciding with the line l, and hence it could collectively be treated as the same line l.
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 537
Joined: Fri Jan 22, 2010 10:06 pmFollowed by: 1 member
Thanked: 14 times

by frank1 » Tue May 18, 2010 3:24 am
sanju09 wrote:
frank1 wrote:Can a straight line be considered as two parallel lines?
We can otherwise say that when two or more lines parallel to a line l are each at zero distance from the line l, then these are all coinciding with the line l, and hence it could collectively be treated as the same line l.
is it yes or no?
you mean to say, it can happen when we take two lines and another point as reference...or two parallel line can overlap?

my logic is then why a single line cannot be considered as two paralle lines
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members
Location: India
Thanked: 267 times
GMAT Score:760

by sanju09 » Tue May 18, 2010 4:45 am
frank1 wrote:
sanju09 wrote:
frank1 wrote:Can a straight line be considered as two parallel lines?
We can otherwise say that when two or more lines parallel to a line l are each at zero distance from the line l, then these are all coinciding with the line l, and hence it could collectively be treated as the same line l.
is it yes or no?
you mean to say, it can happen when we take two lines and another point as reference... (how can I mean something that I myself didn't really get?)or two parallel lineS can overlap (yes, it can)?

my logic is then why a single line cannot be considered as two paralle lines
Dear frank1, my answer to your chief query would then be, not exactly! Why a straight line be considered as only two parallel lines, why not 3, 4, 5 or more? It's analogous to the statement, a zero can be considered as the sum of so many zeros, or a 1 can be considered as the product of so many 1s, etc. Please, reconsider my previous post, it perhaps answers the chief doubt of yours, before hand. Thanks for writing in.
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members
Location: India
Thanked: 267 times
GMAT Score:760

by sanju09 » Tue May 18, 2010 4:57 am
KatieB wrote:I would say both are sufficient on their own in order to find DE:BC. I'm just starting my studying for the GMAT - and as the earlier poster noted the two conditions would lead to different results for DE:BC - so is that a problem or would the answer still be D - EACH statement ALONE is sufficient?
Yes KatieB, that is a problem from the GMAT perspective, GMAT openly slams AMBIGUOUS tag on so many other situations, few of those similar to the one in hand, and no one would ever find on GMAT DS, the two statements, no matter which one suffices or which one not, contradicting one another in one way or the other.

That's why I noted
[spoiler]D, if contradiction within the statements could be overlooked by a mass[/spoiler]
keep writing
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1