早教吧 育儿知识 作业答案 考试题库 百科 知识分享

求值.(cos15°*sin9°+sin6°)/(sin15°*sin9°-cos6°)

题目详情
求值.
(cos15°*sin9°+sin6°)/(sin15°*sin9°-cos6°)
▼优质解答
答案和解析
(cos15°sin9°+sin6°)/(sin15°sin9°-cos6°)
=[cos15sin9+sin(15-9)]/[sin15sin9-(cos15-9)]
=(cos15sin9+sin15cos9-cos15sin9)/(sin15sin9-cos15cos9-sin15sin9)
=(sin15cos9)/(-cos15cos9)
=-tan15
=-sin30/(1+cos30)=根号3 -2.