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2013年新课标全国Ⅰ卷第12题如下:题目设△AnBnCn的三边长分别为an,bn,cn,△AnBnCn的面积为Sn,n=1,2,3,….若b1>c1,b1+c1=2a1,an+1=an,bn+1=(cn+an)/2,cn+1=(bn+an)/2,则()A.S{n}为递减数列B.S{n}为递增数列C.S{2n-1}为递增数列,S{2n}为递减数列D.S{2n-1}为递减数列,S{2n}为递增数列
2013 New Curriculum National Volume I Question No. 12 is as follows: The title set △ AnBnCn the three sides were long, respectively an, bn, cn, △ AnBnCn area Sn, n = 1,2,3 ... .... If b1> c1 () AS {n} is a decreasing sequence of BS {n, b1 + c1 = 2a1, an + 1 = an, bn + 1 = (cn + an) / 2, cn + 1 = } Is an increasing sequence of increments CS {2n-1}, S {2n} is a decreasing sequence DS {2n-1} is a decreasing sequence, S {2n} is an increasing sequence