Last visit was: 28 Apr 2026, 20:27 It is currently 28 Apr 2026, 20:27
Home
Messages
Tests
Schools
Events
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
555-605 (Medium)|   Geometry|      
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 28 Apr 2026
Posts: 109,950
Own Kudos:
811,821
 [5]
Given Kudos: 105,927
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,950
Kudos: 811,821
 [5]
If AD is the same length as DC, what is the area of the parallelogram 07 Sep 2018, 01:08
Kudos
Add Kudos
5
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

35% (medium)

Question Stats:

74% (02:29) correct 26% (02:44) wrong based on 68 sessions

History

Date
Time
Result
Not Attempted Yet

Note: Figure not drawn to scale

If AD is the same length as DC, what is the area of the parallelogram shown?


A. \(\frac{25\sqrt{3}}{2}\)

B. 25

C. \(25\sqrt{3}\)

D. \(\frac{75\sqrt{3}}{2}\)

E. \(50\sqrt{3}\)

Show Spoiler
Attachment:
image023.jpg
image023.jpg [ 4.2 KiB | Viewed 2674 times ]
ShowHide Answer
Official Answer
E
User avatar
saurabh9gupta
User avatar
Joined: 10 Jan 2013
Last visit: 28 Jul 2023
Posts: 251
Own Kudos:
181
Given Kudos: 201
Location: India
Concentration: General Management, Strategy
Schools: Kenan-Flagler '24 (D)
GRE 1: Q163 V155
GPA: 3.95
Products:
My Reviews
Schools: Kenan-Flagler '24 (D)
GRE 1: Q163 V155
Posts: 251
Kudos: 181
If AD is the same length as DC, what is the area of the parallelogram 07 Sep 2018, 02:54
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Since the adjacent angles are supplementary. We can calculate the other angles..

If we drop a perpendicular bisector to the diagonal.. we will get 2 triangles following the 30 60 90 rule.

E

Posted from my mobile device
User avatar
pandeyashwin
User avatar
Joined: 14 Jun 2018
Last visit: 25 Jan 2019
Posts: 165
Own Kudos:
322
Given Kudos: 176
Posts: 165
Kudos: 322
If AD is the same length as DC, what is the area of the parallelogram 07 Sep 2018, 10:53
Kudos
Add Kudos
Bookmarks
Bookmark this Post
You can find the 2nd diagonal using the formula (side)^2 = (1/2* d1)^2 + (1/2 d2)^2
Then area = 1/2 * d1*d2
Ans E
User avatar
PKN
User avatar
Joined: 01 Oct 2017
Last visit: 11 Oct 2025
Posts: 809
Own Kudos:
1,640
 [1]
Given Kudos: 41
Status:Learning stage
WE:Supply Chain Management (Energy)
Posts: 809
Kudos: 1,640
 [1]
If AD is the same length as DC, what is the area of the parallelogram 08 Sep 2018, 00:11
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Using cosine formula of area,

10*10*sin(120)=\(100*\sqrt{3}/2\)=\(50\sqrt{3}\)

Ans. (E)
User avatar
souvonik2k
User avatar
Retired Moderator
Joined: 25 Nov 2015
Last visit: 05 Dec 2021
Posts: 949
Own Kudos:
2,249
 [1]
Given Kudos: 751
Status:Preparing for GMAT
Location: India
GPA: 3.64
Products:
My Reviews
Posts: 949
Kudos: 2,249
 [1]
If AD is the same length as DC, what is the area of the parallelogram 09 Sep 2018, 02:18
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel

Note: Figure not drawn to scale

If AD is the same length as DC, what is the area of the parallelogram shown?


A. \(\frac{25\sqrt{3}}{2}\)

B. 25

C. \(25\sqrt{3}\)

D. \(\frac{75\sqrt{3}}{2}\)

E. \(50\sqrt{3}\)

Show Spoiler
Attachment:
image023.jpg
Show more

Since the adjacent sides are equal, opposite angles are parallel and internal angles are not 90, it is a rhombus.
In rhobus, diagonals bisect each other at rt angles.
Suppose diagonals bisect at O.
In triangle OAB, OA=\(5\sqrt{3}\)
OB = 5 as it is a 30-60-90 triangle.
BD=10
Area=1/2* Product of diagonals = \(\frac{1}{2}*10*10\sqrt{3}=50\sqrt{3}\)
Answer E.
avatar
siddharthfrancis
avatar
Joined: 19 Sep 2016
Last visit: 10 Jan 2022
Posts: 57
Own Kudos:
5
Given Kudos: 292
Posts: 57
Kudos: 5
If AD is the same length as DC, what is the area of the parallelogram 15 Sep 2018, 08:00
Kudos
Add Kudos
Bookmarks
Bookmark this Post
how do u know it is a 30-60-90 triangle.
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,986
Own Kudos:
1,119
Posts: 38,986
Kudos: 1,119
If AD is the same length as DC, what is the area of the parallelogram 05 Nov 2022, 21:24
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Bunuel
Math Expert
109950 posts
Krunaal
Tuck School Moderator
852 posts