A certain circle in the xy-plane has its center at the origin. If P is a point on the circle, what is the sum of the squares of the coordinates of P?
(1) The radius of the circle is 4.
(2) The sum of the coordinates of P is 0.
答案选a
ps：各位知道有tt的讨论帖么。。感觉有的题还是不太懂诶。。 | 
