Last visit was: 04 Sep 2026, 07:12 It is currently 04 Sep 2026, 07:12
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
MathRevolution
User avatar
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Last visit: 27 Sep 2022
Posts: 10,057
Own Kudos:
20,391
 [2]
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Expert
Expert reply
GMAT 1: 760 Q51 V42
Posts: 10,057
Kudos: 20,391
 [2]
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
User avatar
BrentGMATPrepNow
User avatar
Major Poster
Joined: 12 Sep 2015
Last visit: 31 Oct 2025
Posts: 6,727
Own Kudos:
Given Kudos: 799
Location: Canada
Expert
Expert reply
Posts: 6,727
Kudos: 37,231
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 04 Sep 2026
Posts: 11,288
Own Kudos:
46,085
 [1]
Given Kudos: 339
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,288
Kudos: 46,085
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
fskilnik
Joined: 12 Oct 2010
Last visit: 03 Jan 2025
Posts: 883
Own Kudos:
Given Kudos: 57
Status:GMATH founder
Expert
Expert reply
Posts: 883
Kudos: 1,983
Kudos
Add Kudos
Bookmarks
Bookmark this Post
MathRevolution
[Math Revolution GMAT math practice question]

What is the perimeter of a rectangle?

1) The square of the diagonal is \(52\).
2) The area of the rectangle is \(24\).

\(? = {\text{perim}}\left( {{\text{rectangle}}} \right)\)

Excellent opportunity to GEOMETRICALLY BIFURCATE each statement alone:

\(\left( 1 \right)\,\,\,{\text{dia}}{{\text{g}}^{\,{\text{2}}}} = 52\,\,\,\,\,\,\mathop \Rightarrow \limits^{{\text{diag}}\,\, > \,\,0} \,\,\,{\text{diag}}\,\,{\text{unique}}\,\,\,{\text{but}}\,\,\,{\text{INSUFF}}.\)

\(\left( 2 \right)\,\,\,{\text{area}} = 24\,\,\,\,\, \Rightarrow \,\,\,\,{\text{INSUFF}}{\text{.}}\)

(See the image attached!)

\(\left( {1 + 2} \right)\)

Let L and W be the length and width of our focused-rectangle. Hence:

\(? = {\text{2}}\left( {L + W} \right)\)

\(\left( {1 + 2} \right)\,\,\left\{ \begin{gathered}\\
{L^2} + {W^2} = 52 \hfill \\\\
2LW = 2 \cdot 24\,\,\,\, \hfill \\ \\
\end{gathered} \right.\,\,\,\,\mathop \Rightarrow \limits^{\left( + \right)} \,\,\,\,\,{\left( {L + W} \right)^2} = 52 + 48 = 100\)

\({\left( {L + W} \right)^2} = 100\,\,\,\,\mathop \Rightarrow \limits^{L + W\,\, > \,\,0} \,\,\,\,L + W\,\,\,{\text{unique}}\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,\,? = 2\left( {L + W} \right)\,\,\,\,{\text{unique}}\)


This solution follows the notations and rationale taught in the GMATH method.

Regards,
fskilnik.
Attachments

20Set18_5m.gif
20Set18_5m.gif [ 22.84 KiB | Viewed 2713 times ]

User avatar
MathRevolution
User avatar
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Last visit: 27 Sep 2022
Posts: 10,057
Own Kudos:
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Expert
Expert reply
GMAT 1: 760 Q51 V42
Posts: 10,057
Kudos: 20,391
Kudos
Add Kudos
Bookmarks
Bookmark this Post
=>

Forget conventional ways of solving math qAnswer: CAnswer: Cuestions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

When we apply VA method to geometry, we need to count the number of variables. For a rectangle, we have two variables for the length and the width of the rectangle. Let x and y be the length of the width of the rectangle, respectively.

Since we have 2 variables (x and y) and 0 equations, C is most likely to be the answer. So, we should consider conditions 1) & 2) together first. After comparing the number of variables and the number of equations, we can save time by considering conditions 1) & 2) together first.

Conditions 1) & 2)
We have \(x^2+y^2 = 52\) by Pythagoras’ theorem, and \(Area = xy = 24.\)
So, \((x+y)^2 = x^2+2xy + y^2 = (x^2+y^2) +2xy = 52 + 48 = 100.\)
Therefore, \(x+y = 10\) and we can calculate the perimeter.
Both conditions (together) are sufficient.

Therefore, C is the answer.
Answer: C
Moderators:
Math Expert
113128 posts
DI Forum Moderator
409 posts