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 →

OG2018 PS In the figure shown

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Senior | Next Rank: 100 Posts
Posts: 62
Joined: Wed Aug 09, 2017 3:54 pm
by lionsshare » Mon Aug 28, 2017 12:30 pm

Timer

00:00

Answers

A

B

C

D

E

Stats

Difficulty—

Image


In the figure shown, AC = 2 and BD = DC = 1. What is the measure of angle ABD?

A. 15°
B. 20°
C. 30°
D. 40°
E. 45°

OA: C

Please share your solution for this problem.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Newbie | Next Rank: 10 Posts
Posts: 3
Joined: Tue Aug 10, 2010 8:03 am

by fmillar » Tue Aug 29, 2017 12:21 am
Hi there, here comes my first reply ! (let me know if I need to post answers differently)

1) Angle BDC = 60 as it is the complement of ADB (120+60=180)
2) BDC=60 then DBC + DCB = 120, but as BD=DC then DBC=DCB=60 (so an equilateral triangle)
3) Now check that AC =2 but DC=1 therefore AD=1 (AC-DC=2-1)
4) AD =1 but also BD =1 then triangle ADB is isosceles
5) If ADB =120 then DAB+ABD=60 (isosceles), as consequence DAB =30 and ABD=30
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3008
Joined: Mon Aug 22, 2016 6:19 amFollowed by: 34 members
Location: Grand Central / New York
Thanked: 470 times

by Jay@ManhattanReview » Tue Aug 29, 2017 8:41 pm
lionsshare wrote:Image


In the figure shown, AC = 2 and BD = DC = 1. What is the measure of angle ABD?

A. 15°
B. 20°
C. 30°
D. 40°
E. 45°

OA: C

Please share your solution for this problem.
We have to find out the value /_ABD.

We know that AC = 2 and DC = 1, thus AD = AC - DC = 2 - 1 = 1

Thus, in ∆ABD, AD = BD = 1. Thus, it's an isosceles triangle.

/_ABD + /_BDA + /_DAB = 180

2*/_ABD + /_BDA = 180

/_ABD = (180 - 120)/2 = 30

The correct answer: C

Hope this helps!

Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide

-Jay
_________________
Manhattan Review GMAT Prep

Locations: New York | Barcelona | Manila | Melbourne | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8136
Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members
Location: Los Angeles, CA
Thanked: 43 times

by Scott@TargetTestPrep » Wed Nov 15, 2017 3:49 pm
lionsshare wrote:Image


In the figure shown, AC = 2 and BD = DC = 1. What is the measure of angle ABD?

A. 15°
B. 20°
C. 30°
D. 40°
E. 45°
Since AC = 2 and DC = 1, AD must be 1. Since BD = 1, this makes triangle ABD an isosceles triangle with angle D as the vertex angle and angles A and ABD as the base angles. We know that angles A and ABD are equal because the sides opposite them are equal. If we let each of the base angles = x, we can create the following equation:

x + x + 120 = 180

2x = 60

x = 30

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

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] » Tue Jun 12, 2018 4:12 pm
Hi All,

We're told that in the figure shown, AC = 2 and BD = DC = 1. We're asked for the measure of angle ABD.

To start, we know that the drawing is not to scale, so we cannot use the shapes in the picture to estimate an answer. However, we can use any numbers/variables that appear in the picture.

We know that BD and DC are BOTH equal to 1. Since AC equals 2, we know that AD equals 1 (since 2 - 1 = 1). Thus, triangle ABD is ISOSCELES.

We know one of the angles in triangle ABD (re: 120 degrees) and since that triangle is isosceles, the other two angles MUST be equal and total the missing 60 degrees in that triangle. Thus, those two angles are BOTH 30 degrees.

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
Post new topic Post Reply
• Page 1 of 1