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

 It is currently 19 Mar 2019, 14:32

### 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

# Points J(5,2) and K(-2,-5) are two vertices

Author Message
TAGS:

### Hide Tags

Manager
Joined: 13 Aug 2015
Posts: 207
GMAT 1: 710 Q49 V38
GPA: 3.82
WE: Corporate Finance (Retail Banking)
Points J(5,2) and K(-2,-5) are two vertices  [#permalink]

### Show Tags

27 Jun 2017, 15:29
4
00:00

Difficulty:

45% (medium)

Question Stats:

71% (02:39) correct 29% (02:19) wrong based on 55 sessions

### HideShow timer Statistics

Points J(5,2) and K(-2,-5) are two vertices of an isosceles triangle. If L is the third vertex and has a y coordinate of 4, what is the x coordinate of L?

A. -5
B. -4
C. 4
D. 5
E. 6

_________________

If you like my posts, please give kudos. Help me unlock gmatclub tests.

Intern
Joined: 16 Feb 2017
Posts: 20
Re: Points J(5,2) and K(-2,-5) are two vertices  [#permalink]

### Show Tags

27 Jun 2017, 18:44
mkrishnabdrr wrote:
Points J(5,2) and K(-2,-5) are two vertices of an isosceles triangle. If L is the third vertex and has a y coordinate of 4, what is the x coordinate of L?

A. -5
B. -4
C. 4
D. 5
E. 6

In an isosceles triangle only two sides are equal.
Considering JL and KL to be equal in length, we come across at below mentioned algebric equations using distance formula.

$$\sqrt{(x-5)^2+2^2}$$= $$\sqrt{(x+2)^2+9^2}$$

Squaring on both sides

$$(x-5)^2+2^2$$=$$(x+2)^2+9^2$$
$$x^2+25-10x+4=x^2+4+4x+81$$

cancelling $$x^2$$ on both ends

$$29-10x=85+4x$$
$$-14x=56$$
$$x=-4$$

Hope this helps!
Manager
Joined: 13 Aug 2015
Posts: 207
GMAT 1: 710 Q49 V38
GPA: 3.82
WE: Corporate Finance (Retail Banking)
Points J(5,2) and K(-2,-5) are two vertices  [#permalink]

### Show Tags

27 Jun 2017, 18:54
2
GMATAspirer09 wrote:
mkrishnabdrr wrote:
Points J(5,2) and K(-2,-5) are two vertices of an isosceles triangle. If L is the third vertex and has a y coordinate of 4, what is the x coordinate of L?

A. -5
B. -4
C. 4
D. 5
E. 6

In an isosceles triangle only two sides are equal.
Considering JL and KL to be equal in length, we come across at below mentioned algebric equations using distance formula.

$$\sqrt{(x-5)^2+2^2}$$= $$\sqrt{(x+2)^2+9^2}$$

Squaring on both sides

$$(x-5)^2+2^2$$=$$(x+2)^2+9^2$$
$$x^2+25-10x+4=x^2+4+4x+81$$

cancelling $$x^2$$ on both ends

$$29-10x=85+4x$$
$$-14x=56$$
$$x=-4$$

Hope this helps!

This problem is solvable without algebra once we identify that the points J and K are reflection on the line y=-x.
(Reflection of y=-x: (x,y)=(-y,-x)

And any point on the line y=-x will be equidistant from the points J and k.
Hence, if y coordinate =4, then x coordinate =-4

Ans is : B

_________________

If you like my posts, please give kudos. Help me unlock gmatclub tests.

Math Expert
Joined: 02 Sep 2009
Posts: 53709
Re: Points J(5,2) and K(-2,-5) are two vertices  [#permalink]

### Show Tags

27 Jun 2017, 21:07
mkrishnabdrr wrote:
Points J(5,2) and K(-2,-5) are two vertices of an isosceles triangle. If L is the third vertex and has a y coordinate of 4, what is the x coordinate of L?

A. -5
B. -4
C. 4
D. 5
E. 6

This is a copy of the following question: https://gmatclub.com/forum/points-j-3-1 ... 89727.html
_________________
Non-Human User
Joined: 09 Sep 2013
Posts: 10142
Re: Points J(5,2) and K(-2,-5) are two vertices  [#permalink]

### Show Tags

19 Feb 2019, 09:08
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Points J(5,2) and K(-2,-5) are two vertices   [#permalink] 19 Feb 2019, 09:08
Display posts from previous: Sort by