The radius of a circular flower bed is 6m. Now it is necessary to build a sidewalk around the flower bed. The width of the sidewalk is 1.5m. What is the area of the sidewalk in square meters?
一个圆形花坛的半径是6m，现在要在花坛四周修一圈人行道，人行道宽1.5m，人行道面积是多少平方米？
<result>75.36</result>