答案一、选择题DDCBCBCACCDA二、填空题6-13)414)n21-2515)1816)三、解答题17、(1)由正弦定理:3,53sinsincBCbc得5b---------------------------------------------------------5分(2)由余弦定理:212cos222bcacbA,32A0A),,(-------------------------------5分18、(1)202nan------------------------------------------------4分(3)由(1)知:0202nan得10n所以当时或109nn------------------------2分90minns-----------------------------------------------4分19、(1)当1,2yx时----------------------------------------2分5maxu---------------------------------------------1分当3,2yx时----------------------------------------2分9minu-----------------------------------------1分(2)223111)2(222d-----------------------------3分29minv--------------------------------------------------3分20、(1)3C------------------------------------------------------------------4分(3)6233sin21abCabs得----------------------------3分449-cos222222abbaCabbac得-----------------------------------------------3分211ba联立的-------------------------------------------------------------------------------2分、21、方程axaxxaax2,02)2(212得--------------------------------------------1分axaxaaaa22202解集为:时或时,即当----------------------------------------------------------4分axxaaa解集为:时时,即当22----------------------------------------------------------------------------4分axaxaaaa2202-2解集为:时或时,即当-------------------------------------------------------4分22、(1)4,221aa------------------------------------------------------------------------2分(2)Nnnbannn,2,2-------------------------------------------------------4分(3)42)1(2nnnT-------------------------------------------------------------7分