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excellences

For any triangle T in the xy-coordinate plan, the center of T is defined to be the point whose x-coordinate is the average (arithmetic mean) of the x-coordinates of the vertices of T and whose y-coordinate is the average of the y=coordinates of the vertices of T. If a certain triangle has vertices at the points (0,0) and (6,0) and center at the point (3,2), what are the coordinates of the remaining vertex?
A. (3,4)
B. (3,6)
C. (4,9)
D. (6,4)
E. (9,6)
答案B, 我选A, 什么意思啊?

xiaoyue

定义了三角形的中心：X,Y坐标分别为三个顶点的平均数。已知两个顶点和中心坐标，求另一顶点坐标。

(0+6+x)/3=3,得x=3

(0+0+y)/3=2,得y=6