tana2的精选

问题详情：已知数列{an}为等差数列，且a1＋a7＋a13＝4π，则tan(a2＋a12)的值为()(A) (B)－ (C)± (D)－【回答】B.因为a1＋a7＋a13＝4π，所以a7＝，tan(a2＋a12)＝tan＝－，故选B.知识点：数列题型：选择题...