Last visit was: 28 Apr 2026, 06:03 It is currently 28 Apr 2026, 06:03
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
505-555 (Easy)|   Geometry|      
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 28 Apr 2026
Posts: 109,948
Own Kudos:
811,698
 [6]
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: 109,948
Kudos: 811,698
 [6]
In the figure above, triangle CDE is an equilateral triangle with side 07 Sep 2015, 23:02
3
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

15% (low)

Question Stats:

84% (02:08) correct 16% (03:03) wrong based on 168 sessions

History

Date
Time
Result
Not Attempted Yet

In the figure above, triangle CDE is an equilateral triangle with side length 3, AF = 10, EF = 6, and AB = DE. What is the perimeter of the figure?

(A) 45
(B) 36
(C) 29
(D) 24
(E) 16

Kudos for a correct solution.

Show Spoiler
Attachment:
triangles.gif
triangles.gif [ 4.13 KiB | Viewed 7218 times ]
ShowHide Answer
Official Answer
C
User avatar
dominicraj
User avatar
Joined: 05 Apr 2015
Last visit: 27 Jan 2018
Posts: 283
Own Kudos:
752
 [1]
Given Kudos: 39
Products:
My Reviews
Posts: 283
Kudos: 752
 [1]
In the figure above, triangle CDE is an equilateral triangle with side 08 Sep 2015, 01:41
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Using pythagoras theorem,

In triangle AEF
AE=8 and hence AC=5

Again in Triangle ABC,
BC=4

Hence perimeter = 10(AF)+6(EF)+3(DE)+3(DC)+4(BC)+3(AB)=29

Option C.

Regards,
Dom.
User avatar
peachfuzz
User avatar
Joined: 28 Feb 2014
Last visit: 27 Jan 2018
Posts: 268
Own Kudos:
369
 [1]
Given Kudos: 132
Location: United States
Concentration: Strategy, General Management
Products:
My Reviews
Posts: 268
Kudos: 369
 [1]
In the figure above, triangle CDE is an equilateral triangle with side 08 Sep 2015, 11:14
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
[quote="Bunuel"]
AB=3
CD=3
DE=3
AF=10
EF=6

Triangle ABC is a 3-4-5 triangle, so BC=4
3+4+3+3+6+10 = 29

(C) 29
User avatar
shailendra79s
User avatar
Joined: 03 Feb 2014
Last visit: 13 Oct 2016
Posts: 34
Own Kudos:
40
 [1]
Given Kudos: 208
Location: United States
Concentration: Entrepreneurship, General Management
Schools: Stanford Stanford '18 MIT-MSMS'17 HBS '18 Kellogg 1YR '17 Babson 1yr'17
WE:General Management (Other)
Products:
My Reviews
Schools: Stanford Stanford '18 MIT-MSMS'17 HBS '18 Kellogg 1YR '17 Babson 1yr'17
Posts: 34
Kudos: 40
 [1]
In the figure above, triangle CDE is an equilateral triangle with side 08 Sep 2015, 13:18
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
In ▲ AFE, rt. angled at E, AF = 10, EF = 6, → AE² = 10² + 6² → AE = 8;
In ▲ DCE, DC = DE = CE = 3, → AC = AE-CE = 8-3 = 5;
In ▲ ABC, AB = DE =3, AC = 5, BC² = AC² - AB² → BC = 4;
Perimeter of the figure = AB+BC+DC+DE+EF+AF = 3+4+3+3+6+10 = 29;
Answer: C
avatar
harishbiyani8888
avatar
Joined: 12 Nov 2013
Last visit: 18 Dec 2015
Posts: 34
Own Kudos:
993
 [1]
Given Kudos: 141
Posts: 34
Kudos: 993
 [1]
In the figure above, triangle CDE is an equilateral triangle with side 11 Sep 2015, 12:01
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel

In the figure above, triangle CDE is an equilateral triangle with side length 3, AF = 10, EF = 6, and AB = DE. What is the perimeter of the figure?

(A) 45
(B) 36
(C) 29
(D) 24
(E) 16

Kudos for a correct solution.

Show Spoiler
Attachment:
triangles.gif
Show more

Correct answer is C

By using Pythagoras theorem,

In triangle AEF,
AE=8 and hence AC=5

In Triangle ABC,
BC=4

Hence perimeter = 10(AF)+6(EF)+3(DE)+3(DC)+4(BC)+3(AB)

=29
User avatar
sunita123
User avatar
Joined: 13 Oct 2013
Last visit: 09 Mar 2022
Posts: 116
Own Kudos:
299
 [1]
Given Kudos: 530
Concentration: Strategy, Entrepreneurship
Posts: 116
Kudos: 299
 [1]
In the figure above, triangle CDE is an equilateral triangle with side 11 Sep 2015, 12:15
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
perimeter of the figure ABCDEF = AB+BC+CD+DE+EF+AF

everything given except BC.


Calculate AC from the triangle AEF

AC +CE=8 , AC =8-3=5

Now calculate BC

BC = [(AC) 2- (AB)2]^1/2= (25-9)^1/2=4

now perimeter is: AB+BC+CD+DE+EF+AF =3+4+3+3+6+10=29

Ans is C
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 28 Apr 2026
Posts: 109,948
Own Kudos:
811,698
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: 109,948
Kudos: 811,698
In the figure above, triangle CDE is an equilateral triangle with side 14 Sep 2015, 06:40
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel

In the figure above, triangle CDE is an equilateral triangle with side length 3, AF = 10, EF = 6, and AB = DE. What is the perimeter of the figure?

(A) 45
(B) 36
(C) 29
(D) 24
(E) 16

Kudos for a correct solution.

Show Spoiler
Attachment:
The attachment triangles.gif is no longer available
Show more

GROCKIT OFFICIAL SOLUTION:

The question tells us this much:



From here, we can deduce that:

1. Triangle AEF is a 3:4:5 triangle, with side lengths 6:8:10, respectively.

2. Since AE is 8 and CE is 3, that makes AC = 5.

3. Since AC = 5, triangle ABC is also a 3:4:5 triangle, and BC = 4

We can then have:



10+6+4+(3*3) = 29. Answer choice (A) 45 is the sum of the perimeters of each of the triangles, rather than the perimeter of the figure.

Show Spoiler
Attachment:
triangles3.gif
triangles3.gif [ 4.36 KiB | Viewed 6451 times ]
Attachment:
triangles2.gif
triangles2.gif [ 4.31 KiB | Viewed 6519 times ]
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
In the figure above, triangle CDE is an equilateral triangle with side 09 Apr 2023, 11:48
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
109948 posts
Krunaal
Tuck School Moderator
852 posts