* In the xy-plane, point (r,s) lies on a circle with centre

[fahadmuhammad86]

In the xy-plane, point (r,s) lies on a circle with centre at origin. What is the value of r^2+s^2?
1) Radius=2
2) The point sqrt2,-sqrt 2 lies on the circle.

Answer is D.

Im an a little confused about statement 2. How does sqrt2,-sqrt 2 represent (r,s)? It just says that its another point lying on the circle.

[kanikagoyal]

R^2 + S^2 is = the radius^2 of the circle as a right triangle is formed (x=r when y=0 and y=s when x=0)

ie. R^2 + S^2= 2^2=4 (square of radius)

Similarily, R^2 + S^2= (Sqrt2)^2 + (-sqrt2)^2= 4

[Ben Ku]

Please cite the source (author) of this problem. We cannot reply unless a source is cited (and, if no source is cited, we will have to delete the post!). Thanks.

[taniafconca]

This is a question from the second edition verbal book #22.
Explaination would be helpful...

[jnelson0612]

This is a question from the second edition verbal book #22.
Explaination would be helpful...

Do you mean the second edition quantitative book? If so, this source is not allowed on this site; the GMAC does not allow their copyrighted material to be used on this forum.