(1)根据勾股定理求值:
OA 1=
=
;OA 2=
,那么OA 3=
;OA n=
;
(2)S 1=
×1×1=
;S 2=
×
,同理可得S 3=
,S n=
(3)原式=
×(1+100)×100=
.