GWD 数学30套 第24套 11

lxw19

11

An equilateral triangle that has an area of 9 3^1/2 is inscribed in a circle. What is the area of the circle?

A . 6piB. 9piC. 12 piD. 9pi 3^1/2E. 18pi 3^1/2

这道题是什么意思呢 没有看懂啊~~那个pi从哪里来的呢~~求nn