Data Sufficiency

In the xy-plane, point (r,s) lies on a circle with center at the origin. What is the value of r^2 + s^2?

1) The circle has a radius 2.
2) The point (sqrt2, -sqrt2) lies on the circle.



Would someone mind drawing a picture for this. I'm not understanding how to set up this problem.

ANWER [spoiler]{D}[/spoiler]

runningguy wrote:In the xy-plane, point (r,s) lies on a circle with center at the origin. What is the value of r^2 + s^2?

1) The circle has a radius 2.
2) The point (sqrt2, -sqrt2) lies on the circle.



Would someone mind drawing a picture for this. I'm not understanding how to set up this problem.

Step 1: (Simplify):
Consider the following diagram, (r,s) is on the circle and can be any where (depends on the value of r and s). However the question just asks us to find so essentially it is asking us to find the radius of the circle. Restated question => What is the radius of the circle?


Step 2: (Consider the statements 1 and 2)
St1: Gives the radius directly, SUFFICIENT
St2: Gives another point which is again on the circle, and thus by Pythagoras theorem
Thus, radius == 2
SUFFICIENT.

ANSWER is D