a,b为锐角,3sina+3sinb=1 ,3sin(2a)-2sin(2b)=0 求sin(a+2b)
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/05/31 15:38:20
a,b为锐角,3sina+3sinb=1 ,3sin(2a)-2sin(2b)=0 求sin(a+2b)
明如下由COS(A+B)=0,有:
COS(A+B)=cosAcosB-sinAsinB=0
所以cosAcosB=sinAsinB
SIN(A+2B)=sinAcos2B+sin2BcosA
=sinA[(cosB)^2-(sinB)^2]+2sinBcosBcosA
=sinA[(cosB)^2-(sinB)^2]+2sinA(sinB)^2
=sinA[(cosB)^2-(sinB)^2+2(sinB)^2]
=sinA[(cosB)^2+(sinB)^2]
=sinA
COS(A+B)=cosAcosB-sinAsinB=0
所以cosAcosB=sinAsinB
SIN(A+2B)=sinAcos2B+sin2BcosA
=sinA[(cosB)^2-(sinB)^2]+2sinBcosBcosA
=sinA[(cosB)^2-(sinB)^2]+2sinA(sinB)^2
=sinA[(cosB)^2-(sinB)^2+2(sinB)^2]
=sinA[(cosB)^2+(sinB)^2]
=sinA
a,b为锐角,3sina+3sinb=1 ,3sin(2a)-2sin(2b)=0 求sin(a+2b)
已知sinA=3/5 sinB=1/2 A、B均为锐角 求sin(2A+2B)的值
sinb/sina=cos(a+b),证明3sinb=sin(2a+b)
sina+cosb=1/2,cosa+sinb=1/3 求sin(a+b)的值
已知sina+cosb=1/2,cosa+sinb=3/4,求sin(a+b)
已知a、b为锐角,a+b≠π/2,且满足3sinb=sin(2a+b)
已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围
为什么sinA-sinB/sinA+sinB=cos[(A+B)/2]sin[(A-B)/2]/{sin[(A+B)/2
求解一道三角形的问题三角形ABC为锐角三角形,sinA=sin(π/3+B)sin(π/3-B)+sinB(1)求A(2
已知ab为锐角,sina=3/5,sin(a-b)=-1/9,求cosb,sinb
已知cosa-cosb=1/2,sina-sinb=-1/3,求cos(a-b),sin(a+b)
已知sina+sinB=-2/3,cosa-cosB=1/3.求cos(a+B),sin(a+B)