三角函数的化简求值证明11.已知sina-根号3cosa=(4m-6)/(4-m),m≠4,则实数m的取值范围是______________2.设cos(x+π/4)=3/5,17π/12
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/31 03:58:43
![三角函数的化简求值证明11.已知sina-根号3cosa=(4m-6)/(4-m),m≠4,则实数m的取值范围是______________2.设cos(x+π/4)=3/5,17π/12](/uploads/image/z/3015477-45-7.jpg?t=%E4%B8%89%E8%A7%92%E5%87%BD%E6%95%B0%E7%9A%84%E5%8C%96%E7%AE%80%E6%B1%82%E5%80%BC%E8%AF%81%E6%98%8E11.%E5%B7%B2%E7%9F%A5sina-%E6%A0%B9%E5%8F%B73cosa%3D%284m-6%29%2F%284-m%29%2Cm%E2%89%A04%2C%E5%88%99%E5%AE%9E%E6%95%B0m%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4%E6%98%AF______________2.%E8%AE%BEcos%28x%2B%CF%80%2F4%29%3D3%2F5%2C17%CF%80%2F12)
三角函数的化简求值证明11.已知sina-根号3cosa=(4m-6)/(4-m),m≠4,则实数m的取值范围是______________2.设cos(x+π/4)=3/5,17π/12 三角函数的化简求值证明11.已知sina-根号3cosa=(4m-6)/(4-m),m≠4,则实数m的取值范围是______________2.设cos(x+π/4)=3/5,17π/12 1、(-1,7/3)
三角函数的化简求值证明1
1.已知sina-根号3cosa=(4m-6)/(4-m),m≠4,则实数m的取值范围是______________
2.设cos(x+π/4)=3/5,17π/12
1.学过那个公式么
Asina+Bcosa=根号(A^2+B^2)Sin(a+x) 其中TanX=B/A
所以这个题中sina-根号3cosa=2sin(X+一个角度)
他的范围是[-2,2] 所以求的m属于【1,3/7】
2.:∵17π/12<x<7π/4 ∴5π/3<x+π/4<2π,即x+π/4在第四象限,由cos(π/4+x)=3/5,得sin(π/4+x)=-4/5,∴sinx=sin[(x+π/4)-π/4] =sin(x+π/4)*cos(π/4)-cos(x+π/4)*sin(π/4) =(-4/5)*(√2/2)-(3/5)*(√2/2) =-7√2/10 cosx=cos[(x+π/4)-π/4] =cos(x+π/4)*cos(π/4)+sin(x+π/4)*sin(π/4) =(3/5)*(√2/2)+(-4/5)*(√2/2) =-√2/10 ∴sin(2x)=2sins*cosx=2×(-7√2/10)×(-√2/10)=7/25 (sinx)^2=49/50 tanx=sinx/cosx==(-7√2/10)/(-√2/10)=7,∴[sin2x+2(sinx)^2]/(1-tanx) =[7/25+2×(49/50)]/(1-7) =-28/75.
2、-28/75