单选题
If A is the point (-4, 1) and B is the point (2, 1), what is the area of the circle which has AB as a diameter?
A. 3πB. 6πC. 9πD. 12πE. 36π
A. 3πB. 6πC. 9πD. 12πE. 36π
【正确答案】
C
【答案解析】Use TACTIC 1, Chapter 10. Draw a diagram. Since the distance between (-4,1) and (2,1) is 6, the diameter of the circle is 6 and the radius is 3. Then the area is re(3)2 = 9π.
