Last visit was: 23 Apr 2026, 23:43 It is currently 23 Apr 2026, 23:43
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
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 23 Apr 2026
Posts: 109,802
Own Kudos:
Given Kudos: 105,868
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,802
Kudos: 810,901
 [34]
1
Kudos
Add Kudos
32
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
GMATinsight
User avatar
Major Poster
Joined: 08 Jul 2010
Last visit: 23 Apr 2026
Posts: 6,976
Own Kudos:
16,908
 [8]
Given Kudos: 128
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Products:
Expert
Expert reply
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
Posts: 6,976
Kudos: 16,908
 [8]
2
Kudos
Add Kudos
5
Bookmarks
Bookmark this Post
User avatar
PKN
Joined: 01 Oct 2017
Last visit: 11 Oct 2025
Posts: 809
Own Kudos:
1,636
 [5]
Given Kudos: 41
Status:Learning stage
WE:Supply Chain Management (Energy)
Posts: 809
Kudos: 1,636
 [5]
3
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
General Discussion
avatar
Srija221
Joined: 18 Jul 2018
Last visit: 30 Aug 2019
Posts: 29
Own Kudos:
11
 [2]
Given Kudos: 27
Posts: 29
Kudos: 11
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I could not not understand the problem can anyone please explain it a bit more in detail?
User avatar
rraman
Joined: 22 Apr 2018
Last visit: 03 May 2019
Posts: 25
Own Kudos:
47
 [1]
Given Kudos: 78
Posts: 25
Kudos: 47
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
GMATinsight

How do you know tha the Central angle is 120 degree?

Also if we know the know the central angle can we just find the area of the sector and multiply it to 2 to find the shaded region area?
avatar
Sandy56
Joined: 09 Jul 2018
Last visit: 29 Aug 2018
Posts: 8
Own Kudos:
Given Kudos: 10
Posts: 8
Kudos: 2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Can someone provide another solution? I did not really understand the solution above. How can we determine the angle of the diamond shape inside the shaded area?
User avatar
kanthaliya
Joined: 03 Feb 2018
Last visit: 18 Apr 2020
Posts: 58
Own Kudos:
13
 [2]
Given Kudos: 61
Products:
Posts: 58
Kudos: 13
 [2]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel

In the figure above, A and B are the centers of the two circles. If each circle has radius X, what is the area of the shaded region?


A. \(\frac{(2\pi - \sqrt{3}) x^2}{6}\)

B. \(\frac{(4\pi - 3 \sqrt{3}) x^2}{12}\)

C. \(\frac{(4\pi - 3 \sqrt{3}) x^2}{6}\)

D. \(\frac{(4\pi - \sqrt{3}) x^2}{6}\)

E. \(\frac{(6\pi - 1) x^2}{6}\)


Attachment:
circles.jpg


I could not understand why the angle is taken 120. Please help me with its solution.
User avatar
Fdambro294
Joined: 10 Jul 2019
Last visit: 20 Aug 2025
Posts: 1,331
Own Kudos:
772
 [1]
Given Kudos: 1,656
Posts: 1,331
Kudos: 772
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
took me a bit to Understand:


Step 1: Draw the 2 Intersection Points between the Circle and label them A and D, like in the picture above mine.


Step 2: Draw the following Radii = X:

-1- from Center - C1 of the Left Circle to Intersection Point A

-2- from Center -C1 of the Left Circle to Center- C2 of the Right Circle

-3- from Center - C1 of the Left Circle to Intersection Point D


if you label all the Radii = X, you will see that the Diamond Shape in the middle is composed of TWO Equilateral Triangles of Side = X



Step 3: Find Area of Shaded Region:


(1st) Focusing on the Sector Area of the Left Circle. The Central Angle created at Center - C1 with Line Segments X connected to Point A and Point D ----> is a 120 Degree Central Angle.

The Sector Area of this will include the Diamond in the Middle + the Outer Portions OUTSIDE the Diamond but INSIDE Circle A


2nd) Do the Same from the Perspective of the Right Circle. Again, you have the same 120 Degree Central Angle.

This Sector Area will include the Diamond AGAIN in the Middle + the Outer Portions OUTSIDE the Diamond but INSIDE Circle B



3rd) ADD these 2 Equivalent Sector Areas.

This will account for ALL of the Shaded Region. BUT --- we Actually included the DIAMOND AREA TWICE ---- we DOUBLE-COUNTED this Diamond Area


To make up for this Over-Counting, we need to Subtract ONE Area of the DIAMOND Region from the Addition.

Summary:

Area of Shaded Region = 2 * [Sector Area with 120 deg. Central Angle] - [Area of Diamond]




I. Sector Area with 120 deg. Central Angle. Radius = X

(120/360) * (pi) * (X)^2 = (1/3) * (pi) * (X)^2

again, we want to ADD Another to get the entire Region (with the Double-Counted Diamond)

2 * (1/3) * (pi) * (X)^2---- (equation 1)


II. Now, we need to SUBTRACT the Diamond Area to avoid the Double-Counting

the Diamond is composed of 2 Equilateral Triangles with Side = Radius = X

2 * [ (X)^2 * sqrt(3)] / 4 =

1/2 * (X)^2 * sqrt(3) ----- (equation 2)



III. Subtract (equation 2) FROM (equation 1) to get the Correct Area of the Shaded Region


[ 2 * (1/3) * (pi) * (X)^2 ] - [ 1/2 * (X)^2 * sqrt(3) ]


----LCD = 6-----


[(4/6) * (pi) * (X)^2 ] - [(3/6) * (X)^2 * sqrt(3) ]


----take (X)^2 as a Common Factor)

(X)^2 * [ (4 * (pi) - 3 * sqrt(3) / 6]


Answer -C-


I hope it didn't confuse anyone anymore and helped in some little way
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,963
Own Kudos:
Posts: 38,963
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
109802 posts
Tuck School Moderator
853 posts