题目

       California, once regarded as a leader in the United States for its public higher education system, ranks next to the last in the U．S．for its number of adults with at least a high school diploma, according to the report, titled “California at the Edge of a Cliff,” released by the California Faculty Association．        Meanwhile, the state’s investment（投资） in public higher education has dropped over the past three decades, and now ranks 22nd in the country．That’s despite having the country’s largest public higher education system, the report said． �（2009•安顺）下图是我国古代著名的“赵爽弦图”的示意图，它是由四个全等的直角三角形围成的．若AC=6，BC=5，将四个直角三角形中边长为6的直角边分别向外延长一倍，得到如图所示的“数学风车”，则这个风车的外围周长是    ．