Does the curve (x - a)^2 + (y - b)^2 = 16

Oldest

Best Reply

Author

Message

TAGS:

Senior Manager

Joined: 20 Dec 2004

Posts: 268

Followers: 6

Kudos [?]: 43 [0], given: 0

Does the curve (x - a)^2 + (y - b)^2 = 16 [#permalink]

29 Mar 2008, 12:22

00:00

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: 3591

Concentration: Entrepreneurship, Other

Schools: Chicago (Booth) - Class of 2011

GMAT 1: 750 Q50 V40

Followers: 230

Kudos [?]: 1298 [0], given: 346

Re: DS: Curve [#permalink]

29 Mar 2008, 14:09

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.
_________________

iPhone/iPod/iPad: GMAT ToolKit - The bestselling GMAT prep app | GMAT Club (free) | PrepGame | GRE ToolKit | LSAT ToolKit
Android: GMAT ToolKit (NEW!). POLL: What tool do you need next?
Math: GMAT Math Book ||| General: GMATTimer ||| Chicago Booth: Slide Presentation
The People Who Are Crazy Enough to Think They Can Change the World, Are the Ones Who Do.

Find out what's new at GMAT Club - latest features and updates

Senior Manager

Joined: 24 Feb 2008

Posts: 351

Schools: UCSD ($) , UCLA, USC ($), Stanford

Followers: 67

Kudos [?]: 695 [0], given: 2

Re: DS: Curve [#permalink]

29 Mar 2008, 16:32

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: 3591

Concentration: Entrepreneurship, Other

Schools: Chicago (Booth) - Class of 2011

GMAT 1: 750 Q50 V40

Followers: 230

Kudos [?]: 1298 [0], given: 346

Re: DS: Curve [#permalink]

29 Mar 2008, 21:13

Maybe you are right. I like drawing, because it is fastest way for me

_________________

Manager

Joined: 11 Apr 2008

Posts: 157

Schools: Kellogg(A), Wharton(W), Columbia(D)

Followers: 1

Kudos [?]: 53 [0], given: 0

Re: DS: Curve [#permalink]

08 May 2008, 23:24

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 [?]: 168 [0], given: 1

Re: DS: Curve [#permalink]

08 May 2008, 23:41

Neelesh likes Manhattan Math!
_________________

Find out what's new at GMAT Club - latest features and updates

Intern

Joined: 02 Apr 2008

Posts: 37

Followers: 0

Kudos [?]: 10 [0], given: 0

Re: DS: Curve [#permalink]

10 May 2008, 08:40

walker wrote:

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

Re: DS: Curve [#permalink]

10 May 2008, 11:29

How do you know it is a circle with radius 4 just by seeing the equation and not looking at 1 or 2? :oops:

CEO

Joined: 17 Nov 2007

Posts: 3591

Concentration: Entrepreneurship, Other

Schools: Chicago (Booth) - Class of 2011

GMAT 1: 750 Q50 V40

Followers: 230

Kudos [?]: 1298 [0], given: 346

Re: DS: Curve [#permalink]

10 May 2008, 23:13

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? :oops:

(x - a)^2 + (y - b)^2 = r^2 - is a general equation for a circle with center (a,b) and radius of r. So, r=4
_________________

Re: DS: Curve [#permalink] 10 May 2008, 23:13

		Similar topics	Author	Replies	Last post
Similar Topics:		If y = x^2 + c is the equation of a curve, does this curve	crackgmat750	2	19 Sep 2004, 09:36
		If x+y=a and x-y=b, then 2xy=? a) (a^2 - b^2)/2 b)	over13	8	27 Jan 2005, 21:47
	11	Does the curve (x-a)^2 + (y-b)^2=16 intersect the y-axis ?	christoph	8	10 Feb 2005, 13:07
		Does the curve (x-a)^2 + (y-b)^2 = 16 intersect the Y-axis?	ggarr	1	18 Feb 2007, 02:01
		Does curve (x-a)^2 + (y-b)^2 = 16 intersect the Y axis? 1.	bmwhype2	6	28 Nov 2007, 13:48

Does the curve (x - a)^2 + (y - b)^2 = 16

Main navigation

GMAT Resources

Partners

MBA Resources

GMAT ® is a registered trademark of the Graduate Management Admission Council ® (GMAC ®). GMAT Club's website has not been reviewed or endorsed by GMAC.

GMAT Courses

Admissions Consulting

Does the curve (x - a)^2 + (y - b)^2 = 16

Does the curve (x - a)^2 + (y - b)^2 = 16

Main navigation

GMAT Resources

Partners

MBA Resources