gmat preparation courses

It is currently Mon Jan 22, 2018 1:58 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 5 posts ] 
Author Message
 Post subject: GRE Coordinate Geometry (Select One)
PostPosted: Sun Aug 22, 2010 1:19 pm 
Offline

Joined: Sun May 30, 2010 3:15 am
Posts: 424
The two lines y = x and x = -4 intersect on the coordinate plane. What is the value of the area of the figure formed by the intersecting lines and the x-axis?
A. √(46)/3
B. 4√2
C. 8
D. 8√2
E. 16

(C) The lines intersect at the point (-4, -4) and form a right triangle whose base length and height are both equal to 4. As you know, the area of a triangle is equal to one half the product of its base length and height:
A = (1/2) × bh = (1/2) × (4 × 4) = 8
So the area is 8. The correct answer is C.
-------------

Hi, is there a pictorial representation of the triangle that is formed from the above equation?

Thanks.


Top
 Profile  
 
 Post subject: Re: math (test 2, question 20): x,y-plane
PostPosted: Sun Aug 22, 2010 1:30 pm 
Offline

Joined: Sun May 30, 2010 2:23 am
Posts: 498
Here it is:

Image

Triangle ABC is the right triangle (angle ABC = 90 degrees).
AB = 4
BC = 4


Attachments:
triangleABC.gif [5.46 KiB]
Not downloaded yet
Top
 Profile  
 
 Post subject: Re: math (test 2, question 20): x,y-plane
PostPosted: Tue Nov 09, 2010 5:22 pm 
Offline

Joined: Sun May 30, 2010 3:15 am
Posts: 424
Hello,

Based on the information in the stem, to me, the figure that is formed is a square and not a triangle. Since x = -4 forms a straight line parallel to the x-axis and y = x, which translates to y = -4 forms a straight line parallel to the y axis. They both meet at the coordinate (-4.-4), but again, using the x-axis, x = -4 and y = -4 the shape is that of a square not a triangle. Am I missing something?


Top
 Profile  
 
 Post subject: Re: math (test 2, question 20): x,y-plane
PostPosted: Tue Nov 09, 2010 5:35 pm 
Offline

Joined: Sun May 30, 2010 2:23 am
Posts: 498
THE PROPER PICTURE for the question is posted above in this topic.

Note, that the line x = -4 is parallel to the y-axis and crosses the x-axis at the point (-4, 0).

The line y = x and the line y = -4 are different lines. These two lines cross at the point (-4, -4), which happens to be the crossing point of the lines y = x and x = -4 as well.

The following picture demonstrates that the lines y = x and y = -4 are different:

Image
THE PROPER PICTURE for the question is posted above in this topic.


Attachments:
the_lines_-x_equals_y_and_y_equals_-4.gif [4.91 KiB]
Not downloaded yet
Top
 Profile  
 
 Post subject: Re: math (test 2, question 20): x,y-plane
PostPosted: Wed Jan 12, 2011 5:39 pm 
Offline

Joined: Sun May 30, 2010 3:15 am
Posts: 424
Thank you very much!


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group