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 →

Drawbridge - Geometry

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 966
Joined: Sat Jan 02, 2010 8:06 amFollowed by: 21 members
Thanked: 230 times
by shankar.ashwin » Mon Nov 21, 2011 9:03 am
The figure represents the design of a drawbridge that spans a channel 54 meters in width. If the two raisable sections are equal in length and overlap each other by a measure of 2 meters, what will be the clearance width of the bridge in meters, when the sections are raised to an angle of 60 degree ?

A) 25
B) 26
C) 27
D) 28
E) 54
Attachments
Screen shot 2011-11-21 at 10.27.53 PM.png
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 176
Joined: Thu Sep 22, 2011 5:32 am
Thanked: 5 times

by vishal.pathak » Mon Nov 21, 2011 9:15 am
shankar.ashwin wrote:The figure represents the design of a drawbridge that spans a channel 54 meters in width. If the two raisable sections are equal in length and overlap each other by a measure of 2 meters, what will be the clearance width of the bridge in meters, when the sections are raised to an angle of 60 degree ?

A) 25
B) 26
C) 27
D) 28
E) 54
The overlap is 2m. Since the distance is 54 and the over lap is 2, we conclude that each raisable section = (54+2)/2 = 28m

Now the section is raised 60 degree
so the length under this section will be 28*cos(60) = 28*0.5 = 14. The save will be the length under 2nd section. So total length under them is 14*2 = 28
Clearence = 54-28 = 26 IMO
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Community Manager
Posts: 1060
Joined: Fri May 13, 2011 6:46 amFollowed by: 52 members
Location: Utrecht, The Netherlands
Thanked: 318 times

by neelgandham » Mon Nov 21, 2011 9:23 am
From the diagram,
Let x + a be the length of each the raised sections, where a is the length of the overlapping section
Then 2x + a = 54 meters and a = 2 meters,
Implies x = 26 and x+a =28.
Cos 60 = c/(x+a)
0.5 = c /28
c = 14
Clearance width of the bridge,when the sections are raised to an angle of 60 degree = 54 - 2c = 54 -28 = 26

IMO B
Attachments
Beatthegmat_19.JPG
Anil Gandham
Welcome to BEATtheGMAT | Photography | Getting Started | BTG Community rules | MBA Watch
Check out GMAT Prep Now's online course at https://www.gmatprepnow.com/
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 588
Joined: Sun Oct 16, 2011 9:42 amFollowed by: 9 members
Location: New Delhi, India
Thanked: 130 times
GMAT Score:720

by rijul007 » Mon Nov 21, 2011 9:24 am
Length of each section = 54/2 + 1 = 28

check out the image



Image

26/54 = x/54
x = 26/54 * 54 = 26

Option B
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 3
Joined: Sat Aug 23, 2014 7:33 pm

by shrey3192 » Wed Nov 12, 2014 9:31 pm
How come the non parallel sides 28?
How have we come to this..x+a(for hypotenuse)..

Also, why have we subtracted "2" once but not 2 times since its a part of both the sides as in..
why not..x+2+x+2=54(since 2 is a part of both the sides as can be seen from diagram)
Kindly explain..thanx.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

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] » Wed Nov 12, 2014 11:33 pm
Hi shrey3192,

You might find it helpful to draw the two "lines", then lay them on top of one another (as shown in the original drawing).

Here's the basic idea though....

If you had two pieces that were each 28m long and you laid them side by side, you'd have 56m total (28m + 28m = 56m)

However, the two pieces "overlap" 2m....
Lay down the first piece --> that's 28m long
Lay down the second piece, BUT the first 2m of the 2nd piece overlaps with the first piece, so only the remaining 26m creates additional length. 28m + 26m = 54m total.

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: 447
Joined: Fri Nov 08, 2013 7:25 amFollowed by: 1 member
Thanked: 25 times

by Mathsbuddy » Fri Nov 14, 2014 6:42 am
If we consider 2 equilateral triangles (because all angles = 60 deg) overlapping by 2 metres, with their bases aligned, it is clear that the length of side is 54/2 + 1 = 28

If we pull these apart by exactly 2 metres, an inverted equilateral triangle will appear between them. All triangles in this case are congruent (all sideas and angles equal). Therefore it has side length 28 too.

When pushed back in a distance = 2, then the new gap will be 28 - 2 = 26

No need for trigonometry.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1100
Joined: Sat May 10, 2014 11:34 pmFollowed by: 24 members
Location: New Delhi, India
Thanked: 205 times

by GMATinsight » Fri Nov 28, 2014 11:16 pm
shankar.ashwin wrote:The figure represents the design of a drawbridge that spans a channel 54 meters in width. If the two raisable sections are equal in length and overlap each other by a measure of 2 meters, what will be the clearance width of the bridge in meters, when the sections are raised to an angle of 60 degree ?

A) 25
B) 26
C) 27
D) 28
E) 54
Another Perception:

If we displace the two sections such that the overlap becomes zero then the total bottom separation of 54 wll become 54+2 = 56

Now join t he top clearance and the figure will be a composition of three Equilateral triangles with sides 56/2 = 28

Now the top clearance at this point will be 28 which has been increased by 2 as the separation has increased by 2 therefore actual top clearance with overlap = 28-2 = 26

Answer: Option B
"GMATinsight"Bhoopendra Singh & Sushma Jha
Most Comprehensive and Affordable Video Course 2000+ CONCEPT Videos and Video Solutions
Whatsapp/Mobile: +91-9999687183 l [email protected]
Contact for One-on-One FREE ONLINE DEMO Class Call/e-mail
Most Efficient and affordable One-On-One Private tutoring fee - US$40-50 per hour
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1