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 →

What is the length of line segment AB in the figure above?

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Moderator
Posts: 2544
Joined: Sun Oct 15, 2017 1:50 pmFollowed by: 6 members
by BTGmoderatorLU » Sun Dec 03, 2017 1:22 pm
Image

What is the length of line segment AB in the figure above?

A. (√2)/2
B. (√3)/2
C. √2
D. 3/2
E. √3

The OA is C.

I'm really confused with this PS question. Please, can any expert assist me with it? Thanks in advanced.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members
Location: Palo Alto, CA
Thanked: 2867 times
GMAT Score:800

by [email protected] » Sun Dec 03, 2017 7:12 pm
Hi LUANDATO,

I'm going to give you some hints so that you can reattempt this question on your own:

1) The GMAT sometimes "hides" special right triangles (30/60/90, 45/45/90, 3/4/5, 5/12/13) inside of other shapes, so when a prompt includes an uncommon shape, you might try breaking the shape down into 'pieces.'
2) In this question, try cutting the triangle into 2 pieces (draw a line from point A down to the base). You'll form 2 triangles. What do you know about those triangles?
3) With the one side length that you're given, you should be able to fill in all of the other side lengths (although you don't technically have to do all of that work to answer the question that is asked).

Final Answer: C

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 100
Joined: Wed Nov 29, 2017 4:38 pm
Thanked: 14 times

by GMATWisdom » Mon Dec 04, 2017 7:55 pm
LUANDATO wrote:Image

What is the length of line segment AB in the figure above?

A. (√2)/2
B. (√3)/2
C. √2
D. 3/2
E. √3

The OA is C.

I'm really confused with this PS question. Please, can any expert assist me with it? Thanks in advanced.
Use the following formula

a/sinA = b/sinB = c/sinC
where a,b and c are the lengths of the sides of the triangle and A, B and C are the opposite angles.

Based on this,

AC/sin30 = AB/sin45

1/(1/2) = AB/(1/ √2)

Or AB = 2/√2

Or AB = √2

Let me know if this makes sense.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8137
Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members
Location: Los Angeles, CA
Thanked: 43 times

by Scott@TargetTestPrep » Fri Jan 12, 2018 6:40 am
LUANDATO wrote:Image

What is the length of line segment AB in the figure above?

A. (√2)/2
B. (√3)/2
C. √2
D. 3/2
E. √3
If we drop a perpendicular from vertex A to side BC, that is, if we draw the height, we will divide the triangle into two special right triangles: a 45-45-90 triangle on the left and a 30-60-90 triangle on the right. Let's call this height AD, that is, D is a point on BC such that AD is perpendicular to BC.

We know that the side ratio of a 45-45-90 triangle is x : x : x√2. Since AC = 1, we see that if we let AD = x, then x√2 = 1. So x = 1/√2 = √2/2 = AD.

We also know that the side ratio of a 30-60-90 triangle is x : x√3 : 2x. Since AD = √2/2, we see that AB must be twice as much. So AB = 2(√2/2) = √2.

Answer: C

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

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