현재 위치 - 법률 상담 무료 플랫폼 - 회사 전체 - (2014?无锡新区二模)如图,在y轴正半轴上依次截取OA1=A1A2=A2A3=…=An-1An(n为正整数),过点A1,A2,
(2014?无锡新区二模)如图,在y轴正半轴上依次截取OA1=A1A2=A2A3=…=An-1An(n为正整数),过点A1,A2,

设OA1=A1A2=A2A3=…=An-1An=AnAn+1=t,则An的坐标为(0,nt),An+1的坐标为(0,(n+1)t),

∴Pn的坐标为(

2
nt
,nt),Pn+1的坐标为(
2
(n+1)t
,(n+1)t),

∴Sn=

1
2
[
2
nt
+
2
(n+1)t
]?t

=

1
n
+
1
n+1

=

2n+1
n(n+1)

故选D.