It is currently 27 Jun 2017, 07:30

### 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

# ABC and AED are triangles with BC parallel to ED. Find the a

Author Message
TAGS:

### Hide Tags

Manager
Joined: 06 Feb 2013
Posts: 59
ABC and AED are triangles with BC parallel to ED. Find the a [#permalink]

### Show Tags

11 Oct 2013, 03:42
1
This post was
BOOKMARKED
00:00

Difficulty:

25% (medium)

Question Stats:

71% (01:50) correct 29% (01:16) wrong based on 73 sessions

### HideShow timer Statistics

ABC and AED are triangles with BC parallel to ED. Find the area of BCDE if the area of ABC is 16.
Attachment:

Triangle_Barrons.png [ 45.21 KiB | Viewed 2124 times ]

(1) BC = 8
(2) ED = 5
[Reveal] Spoiler: OA

_________________

There are times when I do not mind kudos...I do enjoy giving some for help

Last edited by Bunuel on 11 Oct 2013, 03:43, edited 1 time in total.
Renamed the topic and edited the question.
Math Expert
Joined: 02 Sep 2009
Posts: 39719
Re: ABC and AED are triangles with BC parallel to ED. Find the a [#permalink]

### Show Tags

11 Oct 2013, 03:56
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
ABC and AED are triangles with BC parallel to ED. Find the area of BCDE if the area of ABC is 16.

(1) BC = 8. We don't know where is ED positioned. Not sufficient.
(2) ED = 5. We don't know the other sides. Not sufficient.

(1)+(2) Notice that angles of triangles ABC and AED are equal, which means that the triangles are similar.

Property:
If two similar triangles have sides in the ratio $$\frac{x}{y}$$, then their areas are in the ratio $$\frac{x^2}{y^2}$$.
OR in another way: in two similar triangles, the ratio of their areas is the square of the ratio of their sides: $$\frac{AREA}{area}=\frac{SIDE^2}{side^2}$$.

Since BC/ED=8/5, then $$\frac{AREA_{ABC}}{area_{AED}}=\frac{8^2}{5^2}=\frac{64}{25}$$. As given that the area of ABS is 16, then we can find the area of AED and then find the area of BCDE. Sufficient.

Hope it's clear.
_________________
Manager
Joined: 06 Feb 2013
Posts: 59
Re: ABC and AED are triangles with BC parallel to ED. Find the a [#permalink]

### Show Tags

14 Oct 2013, 04:41
Bunuel wrote:
ABC and AED are triangles with BC parallel to ED. Find the area of BCDE if the area of ABC is 16.

(1) BC = 8. We don't know where is ED positioned. Not sufficient.
(2) ED = 5. We don't know the other sides. Not sufficient.

(1)+(2) Notice that angles of triangles ABC and AED are equal, which means that the triangles are similar.

Property:
If two similar triangles have sides in the ratio $$\frac{x}{y}$$, then their areas are in the ratio $$\frac{x^2}{y^2}$$.
OR in another way: in two similar triangles, the ratio of their areas is the square of the ratio of their sides: $$\frac{AREA}{area}=\frac{SIDE^2}{side^2}$$.

Since BC/ED=8/5, then $$\frac{AREA_{ABC}}{area_{AED}}=\frac{8^2}{5^2}=\frac{64}{25}$$. As given that the area of ABS is 16, then we can find the area of AED and then find the area of BCDE. Sufficient.

Hope it's clear.

Wonderfully done - one question please: "the area of ABC is 16" (in the stimulus) - is there anything we can infer from this information? Or does this information help us in any way before looking at S1 and S2?
_________________

There are times when I do not mind kudos...I do enjoy giving some for help

Math Expert
Joined: 02 Sep 2009
Posts: 39719
Re: ABC and AED are triangles with BC parallel to ED. Find the a [#permalink]

### Show Tags

14 Oct 2013, 04:44
1
KUDOS
Expert's post
obs23 wrote:
Bunuel wrote:
ABC and AED are triangles with BC parallel to ED. Find the area of BCDE if the area of ABC is 16.

(1) BC = 8. We don't know where is ED positioned. Not sufficient.
(2) ED = 5. We don't know the other sides. Not sufficient.

(1)+(2) Notice that angles of triangles ABC and AED are equal, which means that the triangles are similar.

Property:
If two similar triangles have sides in the ratio $$\frac{x}{y}$$, then their areas are in the ratio $$\frac{x^2}{y^2}$$.
OR in another way: in two similar triangles, the ratio of their areas is the square of the ratio of their sides: $$\frac{AREA}{area}=\frac{SIDE^2}{side^2}$$.

Since BC/ED=8/5, then $$\frac{AREA_{ABC}}{area_{AED}}=\frac{8^2}{5^2}=\frac{64}{25}$$. As given that the area of ABS is 16, then we can find the area of AED and then find the area of BCDE. Sufficient.

Hope it's clear.

Wonderfully done - one question please: "the area of ABC is 16" (in the stimulus) - is there anything we can infer from this information? Or does this information help us in any way before looking at S1 and S2?

We just know that the area is 16, we can get nothing more from it.
_________________
Director
Joined: 22 Jun 2014
Posts: 775
Location: United States
Concentration: General Management, Technology
GMAT 1: 540 Q45 V20
GPA: 2.49
WE: Information Technology (Computer Software)
Re: ABC and AED are triangles with BC parallel to ED. Find the a [#permalink]

### Show Tags

09 Dec 2014, 10:11
Hi Bunuel,

Without combining (1) and (2), can't we say both the triangles are similar? i am asking this because i did not understand the reason for insufficiency "We don't know where is ED positioned. Not sufficient."

I marked the answer D because i thought two triangles are similar. Hence, knowing BC=8 will give me the height of the triangle ABC because the area is given. As we know, for similar triangles their ratios of heights and bases are equal i will be able to find the area of triangle AED.

Thanks
_________________

---------------------------------------------------------------
Target - 720-740
http://gmatclub.com/forum/information-on-new-gmat-esr-report-beta-221111.html
http://gmatclub.com/forum/list-of-one-year-full-time-mba-programs-222103.html

Math Expert
Joined: 02 Sep 2009
Posts: 39719
Re: ABC and AED are triangles with BC parallel to ED. Find the a [#permalink]

### Show Tags

09 Dec 2014, 10:36
HKD1710 wrote:
Hi Bunuel,

Without combining (1) and (2), can't we say both the triangles are similar? i am asking this because i did not understand the reason for insufficiency "We don't know where is ED positioned. Not sufficient."

I marked the answer D because i thought two triangles are similar. Hence, knowing BC=8 will give me the height of the triangle ABC because the area is given. As we know, for similar triangles their ratios of heights and bases are equal i will be able to find the area of triangle AED.

Thanks

Yes, we know that they are similar from the stem but this does not help. Check the image below:
Attachment:

Untitled.png [ 49.29 KiB | Viewed 1157 times ]

_________________
Director
Joined: 22 Jun 2014
Posts: 775
Location: United States
Concentration: General Management, Technology
GMAT 1: 540 Q45 V20
GPA: 2.49
WE: Information Technology (Computer Software)
Re: ABC and AED are triangles with BC parallel to ED. Find the a [#permalink]

### Show Tags

09 Dec 2014, 11:12
Bunuel wrote:
HKD1710 wrote:
Hi Bunuel,

Without combining (1) and (2), can't we say both the triangles are similar? i am asking this because i did not understand the reason for insufficiency "We don't know where is ED positioned. Not sufficient."

I marked the answer D because i thought two triangles are similar. Hence, knowing BC=8 will give me the height of the triangle ABC because the area is given. As we know, for similar triangles their ratios of heights and bases are equal i will be able to find the area of triangle AED.

Thanks

Yes, we know that they are similar from the stem but this does not help. Check the image below:
Attachment:
Untitled.png

By looking at the image attached, i understood what you meant by "We don't know where is ED positioned. Not sufficient."

I conclude that in case of similar triangles when the figure is not drawn to scale and value of base for both the triangles is not known then knowing the value of base for only one triangle will always lead to this situation and will be insufficient. Please confirm!

Thank you
_________________

---------------------------------------------------------------
Target - 720-740
http://gmatclub.com/forum/information-on-new-gmat-esr-report-beta-221111.html
http://gmatclub.com/forum/list-of-one-year-full-time-mba-programs-222103.html

Re: ABC and AED are triangles with BC parallel to ED. Find the a   [#permalink] 09 Dec 2014, 11:12
Similar topics Replies Last post
Similar
Topics:
1 Is BC the largest side of triangle ABC? 2 05 Sep 2016, 09:39
3 ABC and AED are triangles with BC and ED perpendicular to AB 1 14 Oct 2013, 05:52
3 The sides AC and BC of ∆ABC are parallel, respectively, to 6 18 Dec 2013, 01:16
3 If A=BC, is A>B ? 5 30 Jan 2013, 06:52
16 What is ∠A in triangle ABC? 19 07 Oct 2015, 04:27
Display posts from previous: Sort by