GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 21 Oct 2018, 22:38

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

Three of the four vertices of a rectangle in the xy-coordinate plane

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 50016
Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

10 Jun 2015, 04:19
11
00:00

Difficulty:

55% (hard)

Question Stats:

67% (02:14) correct 33% (02:13) wrong based on 443 sessions

HideShow timer Statistics

Three of the four vertices of a rectangle in the xy-coordinate plane are ( –5, 1), ( –4, 4), and (8, 0). What is the fourth vertex?

(A) (–4.5, 2.5)
(B) ( –4, 5)
(C) (6, –2 )
(D) (7, –3 )
(E) (10, 1)

Kudos for a correct solution.

_________________
CEO
Joined: 08 Jul 2010
Posts: 2564
Location: India
GMAT: INSIGHT
WE: Education (Education)
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

10 Jun 2015, 07:59
3
4
Bunuel wrote:
Three of the four vertices of a rectangle in the xy-coordinate plane are ( –5, 1), ( –4, 4), and (8, 0). What is the fourth vertex?

(A) (–4.5, 2.5)
(B) ( –4, 5)
(C) (6, –2 )
(D) (7, –3 )
(E) (10, 1)

Kudos for a correct solution.

ALTERNATE

Length of Diagonals are same in a Rectangle

i.e. Distance Between ( –5, 1) and (8, 0) should be same as Distance between ( –4, 4) and 4th Vertex (x, y)

i.e. $$(0-1)^2+(8+5)^2 = (y-4)^2+(x+4)^2$$

i.e. $$1+169 = (y-4)^2+(x+4)^2$$

Check Options:

4th Vertex can only be in either 1st or 4th Quadrant so Option A and B are already out of sync

Option (C) - (6, –2 ): (y-4)^2+(x+4)^2 = (-6)^2 + (10)^2 = 136 so INCORRECT
(D) (7, –3 ): (y-4)^2+(x+4)^2 = (-7)^2 + (11)^2 = 49+121 = 170 so CORRECT

_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

General Discussion
CEO
Joined: 08 Jul 2010
Posts: 2564
Location: India
GMAT: INSIGHT
WE: Education (Education)
Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

10 Jun 2015, 07:51
4
Bunuel wrote:
Three of the four vertices of a rectangle in the xy-coordinate plane are ( –5, 1), ( –4, 4), and (8, 0). What is the fourth vertex?

(A) (–4.5, 2.5)
(B) ( –4, 5)
(C) (6, –2 )
(D) (7, –3 )
(E) (10, 1)

Kudos for a correct solution.

ALTERNATIVE

Slope of Line joining points A( –5, 1) and B( –4, 4) = (4-1) / [(-4)-(-5)] = 3/1 = m1

Slope of Line joining points B( –4, 4) and C( 8, 0) = (0-4) / [(8)-(-4)] = -4/12 = -1/3 = m2

This also suggests that 4th Point must be in Quadrant IV i.e Option C or D only can be true

i.e. AB and BC lines are perpendicular as m1 * m2 = -1

Slope of Line joining points A(–5, 1) and D( x, y) = (y-1) / (x+5) = m3

Slope of Line joining points C(8, 0) and D( x, y) = (y-0) / (x-8) = m4

Now m3 * m4 = -1

i.e. [(y-1) / (x+5)] * [(y-0) / (x-8)] = -1

i.e $$y(y-1) = -(x+5)*(x-8)$$

Let's Check Option C (6, -2)
LHS = (-2)(-2-1) = 6

RHS = (6+5)(6-8) = -22

INCORRECT

Let's Check Option D (7, -3)
LHS = (-3)(-3-1) = 12

RHS = -(7+5)(7-8) = 12

CORRECT

_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Intern
Joined: 10 Jun 2013
Posts: 17
Concentration: General Management, Technology
GMAT Date: 06-26-2015
WE: Corporate Finance (Venture Capital)
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

13 Jun 2015, 06:43
Draw it on the paper, it takes a few seconds to "guess" the correct answer.

Then we could check the result with the formula for the Distance between two points.

Distance btw (-5;1) and (-4;4) is Sqrt(10)

then the correct point must be distant from (8;0) by Sqrt(10)
Current Student
Joined: 02 Jun 2015
Posts: 84
Location: Brazil
Concentration: Entrepreneurship, General Management
GPA: 3.3
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

13 Jun 2015, 08:15
3
Actually this is very easy to be solved if you draw on a paper.

Attachments

P_20150613_121052_1.jpg [ 628.24 KiB | Viewed 9674 times ]

Math Expert
Joined: 02 Sep 2009
Posts: 50016
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

15 Jun 2015, 02:46
1
3
Bunuel wrote:
Three of the four vertices of a rectangle in the xy-coordinate plane are ( –5, 1), ( –4, 4), and (8, 0). What is the fourth vertex?

(A) (–4.5, 2.5)
(B) ( –4, 5)
(C) (6, –2 )
(D) (7, –3 )
(E) (10, 1)

Kudos for a correct solution.

MANHATTAN GMAT OFFICIAL SOLUTION:

Your GMAT scratchpad has a grid; use it to plot the diagram to scale.
Attachment:

2015-06-15_1342.png [ 13.23 KiB | Viewed 9612 times ]

“Eyeball” solution: The corner at ( –4, 4) looks like a right angle, so complete the rectangle with the dashed lines shown. The 4th point must be located approximately where the bigger dot is drawn. The closest answer choice is the point (7, –3 ). Alternatively, you could plot all of the answer choice points and see which one “works” with the three given points.

Alternatively, we could solve by checking the slopes of the solid lines we drew between the given points to prove those lines are perpendicular, that is, to prove we have drawn two sides of the rectangle correctly.

The slope of the long solid line = (4- 0)/(-4 - 8) = -1/3.
The slope of the short solid line = (4 - 1)/(-4 - (-5)) = 3.

The product of these slopes is -1/3*3 = -1, proving that the lines are perpendicular.

Compute the location of the 4th point, using the fact that the short sides have the same slope. The known short side connects the points ( –5, 1) and ( –4, 4). In other words, the bottom left corner is 1 to the left and 3 down from the top left corner. The unknown bottom right corner should therefore be 1 to the left and 3 down from the top right corner, or x = 8 – 1 = 7 and y = 0 – 3 = –3, corresponding to the point (7,–3).

The correct answer is D.
_________________
Intern
Joined: 07 Jun 2015
Posts: 1
Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

28 Jun 2015, 12:19
Bunuel wrote:
Bunuel wrote:
Three of the four vertices of a rectangle in the xy-coordinate plane are ( –5, 1), ( –4, 4), and (8, 0). What is the fourth vertex?

(A) (–4.5, 2.5)
(B) ( –4, 5)
(C) (6, –2 )
(D) (7, –3 )
(E) (10, 1)

Kudos for a correct solution.

MANHATTAN GMAT OFFICIAL SOLUTION:

Your GMAT scratchpad has a grid; use it to plot the diagram to scale.
Attachment:
2015-06-15_1342.png

“Eyeball” solution: The corner at ( –4, 4) looks like a right angle, so complete the rectangle with the dashed lines shown. The 4th point must be located approximately where the bigger dot is drawn. The closest answer choice is the point (7, –3 ). Alternatively, you could plot all of the answer choice points and see which one “works” with the three given points.

Alternatively, we could solve by checking the slopes of the solid lines we drew between the given points to prove those lines are perpendicular, that is, to prove we have drawn two sides of the rectangle correctly.

The slope of the long solid line = (4- 0)/(-4 - 8) = -1/3.
The slope of the short solid line = (4 - 1)/(-4 - (-5)) = 3.

The product of these slopes is -1/3*3 = -1, proving that the lines are perpendicular.

Compute the location of the 4th point, using the fact that the short sides have the same slope. The known short side connects the points ( –5, 1) and ( –4, 4). In other words, the bottom left corner is 1 to the left and 3 down from the top left corner. The unknown bottom right corner should therefore be 1 to the left and 3 down from the top right corner, or x = 8 – 1 = 7 and y = 0 – 3 = –3, corresponding to the point (7,–3).

The correct answer is D.

Hi Bunuel, please explain why the rectangle cant be such that one side joins the points (-5,1) and (8,0), and the opposite side joins the points (-4,4) and the unknown? Thats what I did initially, but it led to a wrong answer. What (apparently obvious) clues did I miss?

My approach was this: two parallel lines have equal slopes so slope for the line joining (-5,1) and (8,0) = slope for the line joining the points (-4,4) and the unknown. For the latter part (slope involving unknown point), x coordinate would be one unit more than (8,0), since the difference b/w x coordinates is 1 unit here: (-5,1) and (-4,4). Then solved for y (the only unknown variable left now).

TIA!
CEO
Joined: 08 Jul 2010
Posts: 2564
Location: India
GMAT: INSIGHT
WE: Education (Education)
Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

28 Jun 2015, 21:59
mrish7 wrote:
Bunuel wrote:
Bunuel wrote:
Three of the four vertices of a rectangle in the xy-coordinate plane are ( –5, 1), ( –4, 4), and (8, 0). What is the fourth vertex?

(A) (–4.5, 2.5)
(B) ( –4, 5)
(C) (6, –2 )
(D) (7, –3 )
(E) (10, 1)

Kudos for a correct solution.

MANHATTAN GMAT OFFICIAL SOLUTION:

Your GMAT scratchpad has a grid; use it to plot the diagram to scale.
Attachment:
2015-06-15_1342.png

“Eyeball” solution: The corner at ( –4, 4) looks like a right angle, so complete the rectangle with the dashed lines shown. The 4th point must be located approximately where the bigger dot is drawn. The closest answer choice is the point (7, –3 ). Alternatively, you could plot all of the answer choice points and see which one “works” with the three given points.

Alternatively, we could solve by checking the slopes of the solid lines we drew between the given points to prove those lines are perpendicular, that is, to prove we have drawn two sides of the rectangle correctly.

The slope of the long solid line = (4- 0)/(-4 - 8) = -1/3.
The slope of the short solid line = (4 - 1)/(-4 - (-5)) = 3.

The product of these slopes is -1/3*3 = -1, proving that the lines are perpendicular.

Compute the location of the 4th point, using the fact that the short sides have the same slope. The known short side connects the points ( –5, 1) and ( –4, 4). In other words, the bottom left corner is 1 to the left and 3 down from the top left corner. The unknown bottom right corner should therefore be 1 to the left and 3 down from the top right corner, or x = 8 – 1 = 7 and y = 0 – 3 = –3, corresponding to the point (7,–3).

The correct answer is D.

Hi Bunuel, please explain why the rectangle cant be such that one side joins the points (-5,1) and (8,0), and the opposite side joins the points (-4,4) and the unknown? Thats what I did initially, but it led to a wrong answer. What (apparently obvious) clues did I miss?

My approach was this: two parallel lines have equal slopes so slope for the line joining (-5,1) and (8,0) = slope for the line joining the points (-4,4) and the unknown. For the latter part (slope involving unknown point), x coordinate would be one unit more than (8,0), since the difference b/w x coordinates is 1 unit here: (-5,1) and (-4,4). Then solved for y (the only unknown variable left now).

TIA!

Hi mrish7,

Considering your argument, the slope of line joining points (-5,1) and (8,0) = -1/13

Now the third point (-4,4) must be joined with (-5, 1) or with (8, 0) to make the other side of rectangle and the new line must have slope of 13 because Product of slopes of two perpendicular lines = -1

Case 1: (-4,4)is joined with (-5, 1), the slope of this line = 3/1

Case 2: (-4,4)is joined with (8, 0) the slope of this line = 4/(-12) = -1/3

Both cases rejected. Therefore this assumption is INCORRECT

I hope it helps!
_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Manager
Joined: 22 Feb 2016
Posts: 94
Location: India
Concentration: Economics, Healthcare
GMAT 1: 690 Q42 V47
GMAT 2: 710 Q47 V39
GPA: 3.57
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

15 Oct 2016, 20:09
Isnt there is a formula to do the same?
x coordinate (x1+x3-x2) and y coordinate (y1+y2-y3)??
Manager
Joined: 22 Feb 2016
Posts: 94
Location: India
Concentration: Economics, Healthcare
GMAT 1: 690 Q42 V47
GMAT 2: 710 Q47 V39
GPA: 3.57
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

15 Oct 2016, 20:14
1
Just derived - The correct formula is
x coordinate- ( x1+x3-x2) and y coordinate is (y1+y3-y2).
CEO
Joined: 08 Jul 2010
Posts: 2564
Location: India
GMAT: INSIGHT
WE: Education (Education)
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

15 Oct 2016, 20:49
AmritaSarkar89 wrote:
Just derived - The correct formula is
x coordinate- ( x1+x3-x2) and y coordinate is (y1+y3-y2).

Although your previous score is already pretty decent but if you are considering taking GMAT again to improve it further then a small piece of advice is "Do away with formulas" as much as possible.

A person getting the score as your profile shows can't be illogical and logical people should understand maths logically. It rewards them with greater score always

In Coordinate geometry, ALWAYS DRAW THE FIGURE while solving questions... It makes your understanding very smooth and easy
_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Manager
Joined: 22 Feb 2016
Posts: 94
Location: India
Concentration: Economics, Healthcare
GMAT 1: 690 Q42 V47
GMAT 2: 710 Q47 V39
GPA: 3.57
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

15 Oct 2016, 21:18
GMATinsight wrote:
AmritaSarkar89 wrote:
Just derived - The correct formula is
x coordinate- ( x1+x3-x2) and y coordinate is (y1+y3-y2).

Although your previous score is already pretty decent but if you are considering taking GMAT again to improve it further then a small piece of advice is "Do away with formulas" as much as possible.

A person getting the score as your profile shows can't be illogical and logical people should understand maths logically. It rewards them with greater score always

In Coordinate geometry, ALWAYS DRAW THE FIGURE while solving questions... It makes your understanding very smooth and easy

Yes I am planning on retaking to hit something close to 750. The problem is since our childhood we had been pushed into memorizing formulas and till date I am struggling to get away with that canopy on my thought process.
Honestly yes, I am trying to logically breakdown every problem
Intern
Joined: 22 Jan 2018
Posts: 7
GPA: 4
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

29 Apr 2018, 10:47
Three of the four vertices of a rectangle in the xy-coordinate plane are ( –5, 1), ( –4, 4), and (8, 0). What is the fourth vertex?

(A) (–4.5, 2.5)
(B) ( –4, 5)
(C) (6, –2 )
(D) (7, –3 )
(E) (10, 1)

Since diagonals of rectangles are Equal ,we can calculate the distance between the diagonals and other two points of vertex must also satisfy that distance .
Points ( –5, 1), and (8, 0) have a distance of sq root of 170 and similarly point ( –4, 4) third vertex and fourth vertex points mentioned in the option must satisfy this distance which is option D(7,-3).
Intern
Joined: 12 Jan 2017
Posts: 10
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

13 May 2018, 09:34
As it’s a rectangle, opposite sides are equal and parallel.
So the slope of the opposites is going to be same m1=m2= 0-4/8+4 =-1/3
As we have the slope and (-5,1) eq of line obtained: 3y+2x=-2.
As it’s already clear that the point will lying in the fourth quadrant, so eliminate options and substitue it on the eq of the line.
Manager
Joined: 29 Sep 2017
Posts: 113
Location: United States
GMAT 1: 720 Q49 V39
GPA: 3.3
WE: Consulting (Consulting)
Re: Three of the four vertices of a rectangle in the xy-coordinate plane  [#permalink]

Show Tags

13 May 2018, 14:57
Without solving, we have y = 1, 4, 0. 1-4 = -3; hence, we need |3| as the difference in y which implies that the last y must be 3 or -3. Only D makes this true so D.
_________________

If this helped, please give kudos!

Re: Three of the four vertices of a rectangle in the xy-coordinate plane &nbs [#permalink] 13 May 2018, 14:57
Display posts from previous: Sort by

Three of the four vertices of a rectangle in the xy-coordinate plane

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.