|
Author |
Message |
|
TAGS:
|
|
|
Senior Manager
Joined: 20 Dec 2004
Posts: 268
Followers: 6
Kudos [?]:
44
[0], given: 0
|
Does the curve (x - a)^2 + (y - b)^2 = 16 [#permalink]
 29 Mar 2008, 12:22
Question Stats:
0% (00:00) correct
 0% (00:00) wrong based on 0 sessions
Does the curve (x - a)^2 + (y - b)^2 = 16 intersect the Y axis? 1. a^2 + b^2 > 16 2. a = |b| + 5
_________________
Stay Hungry, Stay Foolish
|
|
|
|
|
|
|
CEO
Joined: 17 Nov 2007
Posts: 3608
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 240
Kudos [?]:
1322
[0], given: 347
|
B(x - a)^2 + (y - b)^2 = 16 is a circle with center at (a,b) and radius of 4. 1. a^2 + b^2 > 16 presents a plane with a hole at the center of coordinates. So, we can choose (a,b) at Y-axis and far away Y- axis. Insufficient. 2. a = |b| + 5 presents a semi-plane with a>=5. Therefore, any circle with the center at the semi-pane and radius 4 will not intersect Y-axis. Sufficient.
_________________
NEW! GMAT ToolKit 2 (iOS) / GMAT ToolKit (Android) - The must have GMAT prep app | PrepGame
|
|
|
|
|
|
Senior Manager
Joined: 24 Feb 2008
Posts: 351
Schools: UCSD ($) , UCLA, USC ($), Stanford
Followers: 70
Kudos [?]:
719
[0], given: 2
|
I don't understand those plane explanations, Walker. If this is a GMAT problem, there has to be an easier explanations. I paraphrase the question to ask is a in [-4,4], meaning it intersects the Y-axis, or is it not? a is the distance of moving left or right on the X-axis and since we know the radius is 4, a can tell us if the circle intersects the Y-axis. 1. Not sufficient because a can be a number in the interval and outside of it as well. 2. Sufficient because it says a > 5 and that means, a is outside the interval and therefore cannot intersect the Y-axis.
_________________
Chinese Democracy is misunderstood...at your nearest BestBuy.
Best AWA guide here: how-to-get-6-0-awa-my-guide-64327.html
|
|
|
|
|
|
CEO
Joined: 17 Nov 2007
Posts: 3608
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 240
Kudos [?]:
1322
[0], given: 347
|
Maybe you are right. I like drawing, because it is fastest way for me 
_________________
NEW! GMAT ToolKit 2 (iOS) / GMAT ToolKit (Android) - The must have GMAT prep app | PrepGame
|
|
|
|
|
|
Manager
Joined: 11 Apr 2008
Posts: 157
Schools: Kellogg(A), Wharton(W), Columbia(D)
Followers: 1
Kudos [?]:
53
[0], given: 0
|
I found question this sort of tough!! Are such complex problems expected in the real GMAT aor is my coordinate Geo weak?
|
|
|
|
|
|
SVP
Joined: 04 May 2006
Posts: 1946
Schools: CBS, Kellogg
Followers: 10
Kudos [?]:
170
[0], given: 1
|
|
|
|
|
|
|
Intern
Joined: 02 Apr 2008
Posts: 37
Followers: 0
Kudos [?]:
10
[0], given: 0
|
walker wrote: B
(x - a)^2 + (y - b)^2 = 16 is a circle with center at (a,b) and radius of 4.
1. a^2 + b^2 > 16 presents a plane with a hole at the center of coordinates. So, we can choose (a,b) at Y-axis and far away Y- axis. Insufficient.
2. a = |b| + 5 presents a semi-plane with a>=5. Therefore, any circle with the center at the semi-pane and radius 4 will not intersect Y-axis. Sufficient. Walker or anyone: if you could explain how to draw these equations on a plane, it would be very helpful.
|
|
|
|
|
|
Manager
Joined: 27 Jun 2007
Posts: 204
Followers: 3
Kudos [?]:
10
[0], given: 0
|
How do you know it is a circle with radius 4 just by seeing the equation and not looking at 1 or 2? 
|
|
|
|
|
|
CEO
Joined: 17 Nov 2007
Posts: 3608
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 240
Kudos [?]:
1322
[0], given: 347
|
RyanDe680 wrote: How do you know it is a circle with radius 4 just by seeing the equation and not looking at 1 or 2? - is a general equation for a circle with center (a,b) and radius of r. So, r=4
_________________
NEW! GMAT ToolKit 2 (iOS) / GMAT ToolKit (Android) - The must have GMAT prep app | PrepGame
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
close
