函数f(x)=2倍根号3sinxcosx+2cos^2x-1若(x)=6/5,x0属于[兀/4.兀/2],求cos2xo的值,,
函数f(x)=2倍根号3sinxcosx+2cos^2x-1若(x)=6/5,x0属于[兀/4.兀/2],求cos2xo的值,,...
函数f(x)=2倍根号3sinxcosx+2cos^2x-1若(x)=6/5,x0属于[兀/4.兀/2],求cos2xo的值,,
展开
1个回答
展开全部
f(x)=2倍根号3sinxcosx+2cos^2x-1
=√3sin2x+cos2x
=2sin(2x+π/6)
2sin(2x0+π/6)=6/5
sin(2x0+π/6)=3/5 cos(2x0+π/6)=-4/5
cos2xo=cos[(2x0+π/6)-π/6]
=cos(2x0+π/6)cosπ/6+sin(2x0+π/6)sinπ/6
=-4/5*√3/2+3/5*1/2
=(3-4√3)/10
=√3sin2x+cos2x
=2sin(2x+π/6)
2sin(2x0+π/6)=6/5
sin(2x0+π/6)=3/5 cos(2x0+π/6)=-4/5
cos2xo=cos[(2x0+π/6)-π/6]
=cos(2x0+π/6)cosπ/6+sin(2x0+π/6)sinπ/6
=-4/5*√3/2+3/5*1/2
=(3-4√3)/10
本回答由提问者推荐
已赞过
已踩过<
评论
收起
你对这个回答的评价是？
推荐律师服务：
若未解决您的问题，请您详细描述您的问题，通过百度律临进行免费专业咨询
