【正文】
⑦ 已知 ,A,B 為△ ABC的內(nèi)角,則 ∠ C =____ 23,03c o t3 ???,23)15s in (3 ????? ? 033t a n1si n22???? BA??????? 60s i n245t a n250c o t30t a n3① ② ③ ④ ???????? 30c o s45c o s60t a n60c o t45s i n??????? 30co s45s i n145co s60s i n1????? 30s i n1)160( c o s 2???????