Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 29 Jul 2016, 11:14

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# M10: 31

Author Message
Manager
Joined: 12 Aug 2008
Posts: 62
Followers: 2

Kudos [?]: 3 [0], given: 2

### Show Tags

26 Sep 2009, 19:20
If the area of a parallelogram is 100, what is the perimeter of the parallelogram?

1) The base of the parallelogram is 10.
2) One of the angles of the parallelogram is 45 degrees.

Why C and not E?

Am struggling to understand how we can use the pythagorean theorem when we don't know which pair of angles are 45 degrees each in the parallelogram. What am I missing here? Would appreciate some help here.
Manager
Joined: 12 Aug 2008
Posts: 62
Followers: 2

Kudos [?]: 3 [0], given: 2

### Show Tags

27 Sep 2009, 08:24
Anyone
Senior Manager
Joined: 18 Aug 2009
Posts: 328
Followers: 8

Kudos [?]: 263 [1] , given: 13

### Show Tags

27 Sep 2009, 08:44
1
KUDOS
sid3699 wrote:
If the area of a parallelogram is 100, what is the perimeter of the parallelogram?

1) The base of the parallelogram is 10.
2) One of the angles of the parallelogram is 45 degrees.

Why C and not E?

Am struggling to understand how we can use the pythagorean theorem when we don't know which pair of angles are 45 degrees each in the parallelogram. What am I missing here? Would appreciate some help here.

It is not necessary to know which pair of angles is 45 degrees. I have attached an image for your reference.
Attachment:

Parallelogram.jpg [ 14.46 KiB | Viewed 1612 times ]

Please let me know if you want me to explain further
CIO
Joined: 02 Oct 2007
Posts: 1218
Followers: 95

Kudos [?]: 866 [1] , given: 334

### Show Tags

27 Sep 2009, 09:26
1
KUDOS
Hi,

I've drawn a picture to be able to explain the problem better. S1 tells us that AD in the picture below equals 10. If the area of the parallelogram is 100, than its height BD equals $$\frac{100}{10} = 10$$. Now, S2 tells us that one of the angles is 45 degrees. We marked $$\angle BAD$$ as a 45 degrees angle. So, we have an isosceles triangle ABD with BD equal to AD. We know that angle ADB is the right angle and can find AB using the Pythagorean theorem. It will equal $$\sqrt{20}$$, but we don't even have to find the length of the side or calculate the perimeter if we already know we have enough info. You can save some time on these DS question this way.

Did it help? Hope it did .
Attachments

m10-31.png [ 1.83 KiB | Viewed 1606 times ]

_________________

Welcome to GMAT Club!

Want to solve GMAT questions on the go? GMAT Club iPhone app will help.
Result correlation between real GMAT and GMAT Club Tests
Are GMAT Club Test sets ordered in any way?

Take 15 free tests with questions from GMAT Club, Knewton, Manhattan GMAT, and Veritas.

GMAT Club Premium Membership - big benefits and savings

Manager
Joined: 12 Aug 2008
Posts: 62
Followers: 2

Kudos [?]: 3 [0], given: 2

### Show Tags

27 Sep 2009, 14:52
Awesome. Thanks very much.
Joined: 19 Feb 2010
Posts: 401
Followers: 22

Kudos [?]: 160 [0], given: 76

### Show Tags

30 Sep 2011, 08:41
I got this question wrong for a stupid reason (thought "quadrilateral" instead of "parallelogram"). Later it clicked, but it took longer since I got confused reading this piece in the explanation:

Statement (1) by itself is insufficient. We know the base and the height of the parallelogram; however, the height can equal the side of the parallelogram (in case of a rectangle) or it can exceed it.

Statement (2) by itself is insufficient. Nothing can be established about the length of the base of the parallelogram.

Statements (1) and (2) combined are sufficient. The length of the side can be found by the Pythagorean theorem.

As I read it, it was difficult to visualize the height exceeding a side. Am I reading it correctly? How would you correct the bold part?
Intern
Joined: 24 May 2010
Posts: 46
Followers: 0

Kudos [?]: 5 [0], given: 6

### Show Tags

04 Oct 2011, 05:25
sid3699 wrote:
If the area of a parallelogram is 100, what is the perimeter of the parallelogram?

1) The base of the parallelogram is 10.
2) One of the angles of the parallelogram is 45 degrees.

Why C and not E?

Am struggling to understand how we can use the pythagorean theorem when we don't know which pair of angles are 45 degrees each in the parallelogram. What am I missing here? Would appreciate some help here.

Area of parallelogram = base * height = 100. perimeter = 2 (base + side)

St1: base = 10, so height = 10. side is unknown still. not sufficient

St 2: angle = 45. so the triangle formed by base (part) and height is an isosceles triangle 90-45-45. sqrt(2):1:1. so the height and base part should be equal, but unknown.

Both: from St1 base = 10 and height = 10, through st2 side = 10* sqrt(2). As we know side and base, perimeter could be calculated.

C
Intern
Joined: 16 Oct 2011
Posts: 1
Followers: 0

Kudos [?]: 0 [0], given: 0

### Show Tags

28 Nov 2011, 00:34
Why not B?

Since you know that one of the angles is 45 degrees, you can tell that that the parallelogram is made of two 45/45/90 triangles. This would lead you to knowing that the height = the base.

This would lead you to knowing that:

100 = height * base = height * height = base * base

So therefore, height and base must be equal to 10.

And this leads you to knowing that the perimeter must be equal to 20 + 20 * root(2).

Am I missing something or making any leaps of logic that I shouldn't be?

Thanks!
Re: M10: 31   [#permalink] 28 Nov 2011, 00:34
Similar topics Replies Last post
Similar
Topics:
M10, 31 - Parallelogram 1 04 Oct 2009, 17:50
5 m10 q18 16 29 Dec 2008, 23:01
28 M10 Q35 29 21 Dec 2008, 11:13
27 m10 Q13 18 20 Dec 2008, 16:42
20 M10 #04 10 05 Nov 2008, 13:13
Display posts from previous: Sort by

# M10: 31

Moderator: Bunuel

 Powered by phpBB © phpBB Group and phpBB SEO Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.