Figure: http://imageshack.us/photo/my-images/545/circled.jpg/
The figure shows the circle C:
x^2+y^2-6x-2y+9=0. l is a tangent to C. tan B =
A. 0
B. 1/2
C. 3/4
D. 4/3
E. 3/2
圖片參考:http://imgcld.yimg.com/8/n/HA00149615/o/701105180115613873440560.jpg
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