【正文】
??????? c o ss i nc o ss i n)s i n (????????? s i ns i nc o sc o s)c o s (??????????tantan1tantan)t a n(????????? c o ss i nc o ss i n)s i n (???? c o ss i n22s i n????????? s i ns i nc o sc o s)c o s (????? 22 s i nc o s2c o s??????????t a nt a n1t a nt a n)t a n(?????2tan1tan22tan???令???? c o ss i n22s i n????? 22 s i nc o s2c o s?????2tan1tan22tan一、倍角公式 )S( 2?)C( 2?)T( 2?????? 22 s i nc o s2c o s1s i nc o s 22 ???????? 22 s i n1c o s???? 22 c o s1s i n)c o s1(c o s 22 ?????1c o s2 2 ???????? 22 s i n)s i n1(??? 2s i n21???? 2s i n212c o s1c o s22c o