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 Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

In the xy-plane, point (r, s) lies on a circle with center [#permalink]
06 Feb 2006, 16:51

In the xy-plane, point (r, s) lies on a circle with center at the origin. What is the value of
r2 + s2?
(1) The circle has radius 2.
(2) The point (sqrt2, -sqrt2) lies on the circle.

In the xy-plane, point (r, s) lies on a circle with center at the origin. What is the value of r2 + s2? (1) The circle has radius 2. (2) The point (sqrt2, -sqrt2) lies on the circle.

D. since r2 + s2 is redius^2 and both give the value of redius^2.

Can someone help explain this in a little more detail? Ther must be some property of circles that I am not familiar with...

friend, the key fact of this problem is that the distance from the centre of a circle to any point on the circle is equal to the radius of the circle. Here, the centre is the origin of the coordination plane thus:
the distance from the centre to the provided point =
sqrt [ (r-0)^2 + (s-0)^2] = sqrt (r^2 + s^2)
this distance= the radius ---> sqrt(r^2+s^2) = 2 ---> r^2+s^2= 4

---> stmt 1 is suff

stmt 2 already provides us the measure of the radius ---> back to stmt 1 ---> suff

Ah-
I think I was interpreting the question wrong. It says:

joemama142000 wrote:

In the xy-plane, point (r, s) lies on a circle with center at the origin. What is the value of r2 + s2? (1) The circle has radius 2. (2) The point (sqrt2, -sqrt2) lies on the circle.

Can someone help explain this in a little more detail? Ther must be some property of circles that I am not familiar with...

friend, the key fact of this problem is that the distance from the centre of a circle to any point on the circle is equal to the radius of the circle. Here, the centre is the origin of the coordination plane thus: the distance from the centre to the provided point = sqrt [ (r-0)^2 + (s-0)^2] = sqrt (r^2 + s^2) this distance= the radius ---> sqrt(r^2+s^2) = 2 ---> r^2+s^2= 4

---> stmt 1 is suff

stmt 2 already provides us the measure of the radius ---> back to stmt 1 ---> suff

thnk u , i cld ve picked A , but now i understand.
_________________