cosx=1/7,cos(x-y)=13/14,0<y<x<π/2.求y

来源:学生作业帮助网 编辑:作业帮 时间:2024/07/10 19:06:49
cosx=1/7,cos(x-y)=13/14,0<y<x<π/2.求y
x)K/5724*t+5m Mt S @|AHƦJ"}uِc)_.̂jXӎ/fb?_tt̼ [G>cT)+tϲkYsh;m õţ+tXҧAl[ m;KS[j0.7`B-6yv"H

cosx=1/7,cos(x-y)=13/14,0<y<x<π/2.求y
cosx=1/7,cos(x-y)=13/14,0<y<x<π/2.求y

cosx=1/7,cos(x-y)=13/14,0<y<x<π/2.求y
由题意知:cosx=1/7 cos(x-y)=13/14
则通过计算可得:sinx=4√3/7 sin(x-y)=3√3/14
用余弦公式:cosx·cos(x-y)+sinx·sin(x-y)=cos[x-(x-y)]=cosy
即cosy=(1/7·13/14)+(4√3/7·3√3/14)=1/2
cosy=0.5 y=π/3