题目 举报tan18度等于多少?扫码下载作业帮搜索答疑一搜即得
答案解析 查看更多优质解析解答一举报sin3*18=3sin18-4sin^318cos36=1-2sin^218sin54=cos363sin18-4sin^318=1-2sin^2184sin^318-2sin^218-3sin18+1=0(sin18-1)(4sin^218+2sin18-1)=0sin18=(√5-1)/4cos18=√(10+2√5)/4tan18=(√5-1)/√(10+2√5)解析看不懂？免费查看同类题视频解析查看解答