Source: Official Guide Revised GRE 1st Ed. Part 8; Section 6; #14

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# n the xy-plane, the point with coordinates

In the xy-plane, the point with coordinates (?6, ?7) is the center of circle C. The point with coordinates (?6, 5) lies inside C, and the point with coordinates (8, ?7) lies outside C. If m is the radius of C and m is an integer, what is the value of m? m =

### 3 Explanations

3

Rachit Singh

Why can't we take the origin as the pivot and find the radius using the coordinates (0,0) & , (-6,-7). Though this will come in decimals, why is my approach incorrect.?

Sep 20, 2016 • Comment

Sam Kinsman, Magoosh Tutor

Hi there Rajendra! Keep in mind that (0, 0) is not the center of the circle. The center of the circle is (6, 7). The point (0, 0) is actually somewhere inside the circle - so if we find the distance between (6, 7) and (0, 0), that doesn't help us find the radius.

1

Jordana Schiralli

Why can't m = 12?

Sep 12, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Happy to help, Jordana! If m = 12, then the point (-6, 5), which is 12 units above the center of the circle, would lie on the circle itself. However, since we're told that (-6, 5) in inside the circle, then the radius must be greater than the distance between the center (-6, -7) and the point inside the circle (-6, 5).

Hope this helps!

3 Chris Lele, Magoosh Tutor

Oct 11, 2012 • Comment