欲使四边形QPCP'为菱形,必须PC=PQ(AC-AD)²+PD²=PE²+(BC-EC-BQ)²∵AP=√2t,∴AD=PD=EC=t(6-t)²+t²=(6-t)²+(6-t-t)²化简为：t²-8t+12=0(t-2)(t-6)=0∴t1=2,t2=6（舍...