sin(2a-b)-2cos(a+b)sina/sinb

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/07/01 11:24:51

sin(2a-b)-2cos(a+b)sina/sinb
=sin(2a-b)-2[sinacosacosb-sinasinasinb]/sinb
=sin(2a-b)-sin2acotb+2sin^2(a)
=sin(2a-b)-sin2acotb+1-cos2a
=sin2acosb-cos2asinb-sin2acotb+1-cos2a
=sin2acosb-sin2acotb-cos2asinb-cos2a+1
=sin2a(cosb-cotb)-cos2a(sinb+1)+1

为什么sinA-sinB/sinA+sinB=cos[(A+B)/2]sin[(A-B)/2]/{sin[(A+B)/2 sinb/sina=cos(a+b),证明3sinb=sin(2a+b) 证明sin(2a+b)/sina-2cos(a+b)=sinb/sina 求证sin(2A+B)/sinA-2cos(A+B)=sinB/sinA 三角形ABC中,为什么sinA+sinB=2sin(A+B)/2*cos（A-B)/2 求证sina+sinb=2sin(a+b)/2*cos(a-b)/2 为什么sina+sinb==2sin(a+b)\/2*cos(a-b)\/2 如何证明sinA+sinB=2sin((A+B)/2)cos((A-B)/2) 为什么sina+sinb==2sin(a+b)/2*cos(a-b)/2 sinA+sinB 怎么变成2sin[（A+B)\2]cos[(A-B)\2] sinA+sinB=2sin((A+B)/2)cos((A-B)/2 sina+sinb=2sin((a+b)/2)cos((a-b)/2的推导过程