Back to Questions
GRE Quantitative Reasoning
QUESTION #8183
Question 1
In the $xy$-plane, circle $C$ has center at $(-6,\ -7)$. The point $(-6,\ 5)$ lies inside the circle, and the point $(8,\ -7)$ lies outside the circle. If the radius $m$ of circle $C$ is an integer, what is the value of $m$?
Correct Answer Explanation
The distance from the center $(-6, -7)$ to the inside point $(-6, 5)$:
$d_1 = \sqrt{(-6-(-6))^2 + (5-(-7))^2} = \sqrt{0 + 144} = 12$
Since $(-6, 5)$ is inside the circle: $m > 12$.
The distance from the center $(-6, -7)$ to the outside point $(8, -7)$:
$d_2 = \sqrt{(8-(-6))^2 + (-7-(-7))^2} = \sqrt{196 + 0} = 14$
Since $(8, -7)$ is outside the circle: $m < 14$.
So $12 < m < 14$, and $m$ is an integer, therefore $m = \mathbf{13}$.
Sign in to join the conversation and share your thoughts.
Log In to Comment