过D作DH⊥AC于H,得等腰Rt△CDHCD=6-x,∴DH=(6-x)/√2∵DE∥AB,∴BD/CD=AE/CE即x/(6-x)=AE/(4√2-AE)化简得AE=x*2√2/3∴y=1/2*AE*DH=2x-x²/3(0
