【正文】
= . 計(jì)算: )425t a n(325c os625s in ??? ???= . 化簡(jiǎn):)(c os)5s i n ()4s i n ( )3(s i n)(c os)4c os ( 222?????? ?????? ???? ???= ______ ___. 已知 ? ? ? ?? ? ? ? 29c oss in4 c oss in3 ???? ??? ??? ???,則 ?tan = . 若 a??tan ,則 ? ? ? ????? ??? 3c o s5s in = ____ ____. 化簡(jiǎn) :)29s i n ()s i n ()3s i n ()c o s ()211