(2013•定海区模拟)如图,已知Rt△ABC中,AC=b,BC=a,D1是斜边AB的中点,过D1作D1E1⊥AC于E1
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(2013•定海区模拟)如图,已知Rt△ABC中,AC=b,BC=a,D
1是斜边AB的中点,过D
1作D
1E
1⊥AC于E
1,连结BE
1交CD
1于D
2;过D
2作D
2E
2⊥AC于E
2,连结BE
2交CD
1于D
3;过D
3作D
3E
3⊥AC于E
3,…,如此继续,可以依次得到点D
4,D
5,…,D
n,分别记△BD
1E
1,△BD
2E
2,△BD
3E
3,…,△BD
nE
n的面积为S
1,S
2,S
3,…S
n.则S
n为( )
A.
B.
C.[ab
n2 |