已知cos(π/4+x)=3/5,(1π)12
问题描述:
已知cos(π/4+x)=3/5,(1π)12
答
您好:
解答如下
17π/12
cosx=cos(π/4 +x-π/4 )
=cos(π/4 +x)cosπ/4+sin(π/4 +x)sinπ/4
=3/5×√2/2+(-4/5)×√2/2
=-√2/10
因为17π/12
(sin2x+2sin²x)/1-tanx=(7/25+49/25)/(1-7)=-28/75
谢谢采纳,有疑问欢迎您追问