A:4b+9a=1
B:4b-9a=1
C:3a+2b=1
D:4b+9a=-1
--- Lily's never been to Hainan, has she? ---______, but she will visit it next summer.
如图,⊙I为△ABC的内切圆,AB=9,BC=8,AC=10,点D、E分别为AB、AC上的点,且DE为⊙I的切线,则△ADE的周长为 ____