In the figure above, three congruent circles with center A, B, and C are tangent to each other at M, N, and O. If BO = 18, what is the area of one of the circles?
Options
A
B
72π
C
81π
D
108π
Answer & Analysis
Answer
D
Analysis
According to the given information, we can simply connect the centers to reveal the tangle.
As all circles are congruent, all their radius are congruent. Therefore, BO = 18 is a perpendicular bisector of an equilateral triangle. So △ABO and △CBO are two 30-60-90 triangles.
The sides in a 30-60-90 are in a ratio. The 18 we
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