the circle has center O and radius 50, and point P has coordinates
(50,0). If point Q (not shown) is on the circle, what is the length of line segment PQ ?
(1) The x-coordinate of point Q is – 30.
(2) The y-coordinate of point Q is – 40.
9
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is
sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

我想知道如果不知道Q点的具体棕坐标，怎样求出PQ的长度？此题我选C

条件1告诉你Q的X座标是-30啦~~Q又在圆O（X^2+Y^2=2500）上，那么Y轴的坐标

可以求出为+-40

因为Q1(-30，-40)和Q2（-30,40）关于X轴对称，到点P（50，0）的距离相等

所以凭条件1ALONE可以得出PQ长度