Last visit was: 22 Apr 2026, 15:04 It is currently 22 Apr 2026, 15:04
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
AbhiJ
User avatar
Retired Moderator
Joined: 10 May 2010
Last visit: 30 Jul 2022
Posts: 793
Own Kudos:
648
 [44]
Given Kudos: 192
8
Kudos
Add Kudos
36
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
anairamitch1804
Joined: 26 Oct 2016
Last visit: 20 Apr 2019
Posts: 502
Own Kudos:
3,605
 [5]
Given Kudos: 877
Location: United States
Concentration: Marketing, International Business
Schools: HBS '19
GMAT 1: 770 Q51 V44
GPA: 4
WE:Education (Education)
Schools: HBS '19
GMAT 1: 770 Q51 V44
Posts: 502
Kudos: 3,605
 [5]
2
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
General Discussion
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 22 Apr 2026
Posts: 109,754
Own Kudos:
810,663
 [3]
Given Kudos: 105,823
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,754
Kudos: 810,663
 [3]
2
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
User avatar
devpanda
Joined: 28 Sep 2011
Last visit: 04 Dec 2013
Posts: 18
Own Kudos:
21
 [2]
Given Kudos: 18
Location: India
WE:Consulting (Computer Software)
Posts: 18
Kudos: 21
 [2]
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
I still have doubt.
1. If we consider, the height to be diameter, then wouldnt just A suffice

Bunuel
AbhiJ
A trapezoid is symmetrical about a vertical center line. If a circle is drawn such that it is tangent to exactly three sides of the trapezoid and is enclosed entirely within the trapezoid, what is the diameter of the circle

(1) The parallel sides of the trapezoid are 10 inches apart.
(2) Of the parallel sides of the trapezoid, the shorter side is 15 inches long.


Will appreciate an algebraic proof.

Given; the circle is is entirely enclosed within the isosceles trapezoid, so that it is tangent to exactly three sides

Below is the only case possible to satisfy the following conditions:
1. Height is 10.
2. Shorter base is 15.
Attachment:
Trapezoid.png
So, diameter of the circle is 10.

Answer: C.
avatar
raingary
Joined: 22 Jan 2012
Last visit: 07 Oct 2012
Posts: 25
Own Kudos:
Posts: 25
Kudos: 84
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I too thought the same , then with 1 you can fix the distance between the parallel sides of the trapezoid , but will not be able to restrict the size of the trapezoid until unless there is some extra info to do that , which here is the shorter side in 2.
User avatar
AbhiJ
User avatar
Retired Moderator
Joined: 10 May 2010
Last visit: 30 Jul 2022
Posts: 793
Own Kudos:
648
 [2]
Given Kudos: 192
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
If we consider the case when the circle touches the two equal sides of isosceles trapezium and the shorter side, here I am not able to prove rigorously that the distance between the two parallel sides must be more than 10.
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 22 Apr 2026
Posts: 109,754
Own Kudos:
810,663
 [5]
Given Kudos: 105,823
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,754
Kudos: 810,663
 [5]
4
Kudos
Add Kudos
Bookmarks
Bookmark this Post
devpanda
I still have doubt.
1. If we consider, the height to be diameter, then wouldnt just A suffice

Bunuel
AbhiJ
A trapezoid is symmetrical about a vertical center line. If a circle is drawn such that it is tangent to exactly three sides of the trapezoid and is enclosed entirely within the trapezoid, what is the diameter of the circle

(1) The parallel sides of the trapezoid are 10 inches apart.
(2) Of the parallel sides of the trapezoid, the shorter side is 15 inches long.


Will appreciate an algebraic proof.

Given; the circle is is entirely enclosed within the isosceles trapezoid, so that it is tangent to exactly three sides

Below is the only case possible to satisfy the following conditions:
1. Height is 10.
2. Shorter base is 15.
Attachment:
The attachment Trapezoid.png is no longer available
So, diameter of the circle is 10.

Answer: C.

Consider the diagram below for statement (1):
Attachment:
1.png
1.png [ 6.92 KiB | Viewed 12991 times ]
As you can see we have two circles with different radii.
User avatar
varunmaheshwari
Joined: 25 Aug 2008
Last visit: 28 Jun 2012
Posts: 99
Own Kudos:
Given Kudos: 5
Location: India
WE 1: 3.75 IT
WE 2: 1.0 IT
Posts: 99
Kudos: 334
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I agree with Bunuel..
Both are needed to understand which combination of sides will be touching the circle.
Is it 1 Non-Parallel side and 2 Parallel sides OR 2 Non-Parallel sides and 1 Parallel side.
avatar
Prashant85
Joined: 17 Jan 2012
Last visit: 07 May 2012
Posts: 2
Own Kudos:
Given Kudos: 4
Location: United States
Concentration: Operations, Marketing
GMAT Date: 05-10-2012
WE:Engineering (Energy)
Posts: 2
Kudos: 5
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I have a doubt..
there is also this statement in the question that "the trapezoid is symmetrical about a vertical line". But the solution is arrived by assuming it symmetrical about a horizontal line.??
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 22 Apr 2026
Posts: 109,754
Own Kudos:
810,663
 [1]
Given Kudos: 105,823
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,754
Kudos: 810,663
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Prashant85
I have a doubt..
there is also this statement in the question that "the trapezoid is symmetrical about a vertical line". But the solution is arrived by assuming it symmetrical about a horizontal line.??

Vertical line: |

The trapezoid is symmetrical about a vertical line (|) means that the trapezoid is isosceles.
User avatar
varunmaheshwari
Joined: 25 Aug 2008
Last visit: 28 Jun 2012
Posts: 99
Own Kudos:
334
 [1]
Given Kudos: 5
Location: India
WE 1: 3.75 IT
WE 2: 1.0 IT
Posts: 99
Kudos: 334
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Nope.. The solutions is arrived by considering the statement that "the trapezoid is symmetrical about a vertical line".
It cannot have non parallel sides on the y-aixs if it was assumed that the trapezoid is symmetrical about a horizontal line because the non parallel sides will intersect at some point..
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 22 Apr 2026
Posts: 109,754
Own Kudos:
Given Kudos: 105,823
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,754
Kudos: 810,663
Kudos
Add Kudos
Bookmarks
Bookmark this Post
varunmaheshwari
Nope.. The solutions is arrived by considering the statement that "the trapezoid is symmetrical about a vertical line".
It cannot have non parallel sides on the y-aixs if it was assumed that the trapezoid is symmetrical about a horizontal line because the non parallel sides will intersect at some point..

What you mean "nope"?

Stem says "a trapezoid is symmetrical about a vertical center line" which means that that the trapezoid is isosceles. All diagrams show trapezoids which are symmetrical about a vertical center line.
User avatar
varunmaheshwari
Joined: 25 Aug 2008
Last visit: 28 Jun 2012
Posts: 99
Own Kudos:
Given Kudos: 5
Location: India
WE 1: 3.75 IT
WE 2: 1.0 IT
Posts: 99
Kudos: 334
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel,
The nope was for Prashant85 question that the solution is arrived by assuming it symmetrical about a horizontal line..
I think we both started answering at the same time and that's why I missed you answer while posting mine..
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 22 Apr 2026
Posts: 109,754
Own Kudos:
Given Kudos: 105,823
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,754
Kudos: 810,663
Kudos
Add Kudos
Bookmarks
Bookmark this Post
varunmaheshwari
Bunuel,
The nope was for Prashant85 question that the solution is arrived by assuming it symmetrical about a horizontal line..
I think we both started answering at the same time and that's why I missed you answer while posting mine..

That's why I didn't understand your response. I guess all is clear then.
avatar
Prashant85
Joined: 17 Jan 2012
Last visit: 07 May 2012
Posts: 2
Own Kudos:
Given Kudos: 4
Location: United States
Concentration: Operations, Marketing
GMAT Date: 05-10-2012
WE:Engineering (Energy)
Posts: 2
Kudos: 5
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Thanks Bunuel and Varun...
Its clear now.
User avatar
jayaddula
Joined: 03 Apr 2012
Last visit: 08 Feb 2014
Posts: 17
Own Kudos:
Given Kudos: 10
Posts: 17
Kudos: 27
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
AbhiJ
A trapezoid is symmetrical about a vertical center line. If a circle is drawn such that it is tangent to exactly three sides of the trapezoid and is enclosed entirely within the trapezoid, what is the diameter of the circle

(1) The parallel sides of the trapezoid are 10 inches apart.
(2) Of the parallel sides of the trapezoid, the shorter side is 15 inches long.


Will appreciate an algebraic proof.

Given; the circle is is entirely enclosed within the isosceles trapezoid, so that it is tangent to exactly three sides

Below is the only case possible to satisfy the following conditions:
1. Height is 10.
2. Shorter base is 15.
Attachment:
Trapezoid.png
So, diameter of the circle is 10.

Answer: C.

Hi Bunuel,
Why can't you have a circle touching the isosceles side, in which case the radius is 15. I did not understand your solution. could you please explain.

thank you
User avatar
AbhiJ
User avatar
Retired Moderator
Joined: 10 May 2010
Last visit: 30 Jul 2022
Posts: 793
Own Kudos:
Given Kudos: 192
Kudos
Add Kudos
Bookmarks
Bookmark this Post
jayaddula
Bunuel
AbhiJ
A trapezoid is symmetrical about a vertical center line. If a circle is drawn such that it is tangent to exactly three sides of the trapezoid and is enclosed entirely within the trapezoid, what is the diameter of the circle

(1) The parallel sides of the trapezoid are 10 inches apart.
(2) Of the parallel sides of the trapezoid, the shorter side is 15 inches long.


Will appreciate an algebraic proof.

Given; the circle is is entirely enclosed within the isosceles trapezoid, so that it is tangent to exactly three sides

Below is the only case possible to satisfy the following conditions:
1. Height is 10.
2. Shorter base is 15.
Attachment:
Trapezoid.png
So, diameter of the circle is 10.

Answer: C.

Hi Bunuel,
Why can't you have a circle touching the isosceles side, in which case the radius is 15. I did not understand your solution. could you please explain.

thank you
This is my doubt as well, I can see how it is true from the diagram. However when I try to prove it mathematically , i fail.
avatar
riteshgupta
Joined: 11 Jun 2011
Last visit: 24 Aug 2012
Posts: 3
Own Kudos:
7
 [1]
Given Kudos: 6
Posts: 3
Kudos: 7
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
jayaddula
Bunuel
AbhiJ
A trapezoid is symmetrical about a vertical center line. If a circle is drawn such that it is tangent to exactly three sides of the trapezoid and is enclosed entirely within the trapezoid, what is the diameter of the circle

(1) The parallel sides of the trapezoid are 10 inches apart.
(2) Of the parallel sides of the trapezoid, the shorter side is 15 inches long.


Will appreciate an algebraic proof.

Given; the circle is is entirely enclosed within the isosceles trapezoid, so that it is tangent to exactly three sides

Below is the only case possible to satisfy the following conditions:
1. Height is 10.
2. Shorter base is 15.
Attachment:
Trapezoid.png
So, diameter of the circle is 10.

Answer: C.

Hi Bunuel,
Why can't you have a circle touching the isosceles side, in which case the radius is 15. I did not understand your solution. could you please explain.

thank you

Hi Jayaddula,
If we take only option B, then the diameter is >15 and not 15, i.e. it can be any number, so we can't say B.
Now for C If we have circles touching the isosceles sides, then the diameter will be >15 and not 10, i.e. the circle will not be inside the Trapezoid. This implies that circle will touch the parallel sides and not the non-parallel sides of the Trapezoid.Thus the two statements together are sufficient to answer the question.
Hope I am clear.
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,966
Own Kudos:
Posts: 38,966
Kudos: 1,117
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:
Math Expert
109754 posts
498 posts
212 posts