sin（a+b)=0.2.cos(a-b)=0.8.求tana/tan不好意思是求tana /tanb

来源：学生作业帮助网 编辑：六六作业网 时间：2025/01/24 13:23:18
sin（a+b)=0.2.cos(a-b)=0.8.求tana/tan不好意思是求tana/tanbsin（a+b)=0.2.cos(a-b)=0.8.求tana/tan不好意思是求tana/tanb

sin（a+b)=0.2.cos(a-b)=0.8.求tana/tan不好意思是求tana /tanb
sin（a+b)=0.2.cos(a-b)=0.8.求tana/tan
不好意思
是求tana /tanb

sin（a+b)=0.2.cos(a-b)=0.8.求tana/tan不好意思是求tana /tanb
补充完整吧
条件cos(a-b)=0.8可转换为sin(a-b)=0.6
这样把条件展开得：
sinacosb+cosasina=0.2 ①
sinacosb-cosasinb=0.6 ②
①/②得：（sinacosb+cosasina）/（sinacosb-cosasinb）=1/3 ③
③的左边分子分母都除以cosacosb得：（tana+tanb）/（tana-tanb）=1/3 ④
设x=tana /tanb,则tana=xtanb；带入④得：（xtanb+tanb）/（xtanb-tanb）=1/3
即：（x+1）/（x-1）=1/3
解得x=-2即tana /tanb=-2

如何证明sin(a+b)=sin(a)cos(b)+cos(α)sin(b) cos(a-b)cos(b-c)+sin(a-b)sin(b-c)= cos^2a-cos^2b=m,那么sin(a+b)sin(a-b)=? cos²a-cos²b=c,则sin(a+b)sin(a-b)= cos∧a-cos∧b=t则sin(a+b)sin(a-b)= 证明sin(A+B)sin(A-B)=cos^2B-cos^2A 求证cos(a+b)cos(a－b)=cos^2b－sin^2a 求证cos(a+b)cos(a-b)=cos^2a-sin^2b 求证:cos(a+b)cos(a-b)=cos平方b-sin平方a 求证:cos²a-sin²b=cos(a-b)cos(a+b) cos(a+b)=sin(a-b) 求tan a sin a sin b +cos a cos b =0,则sin a cos a+sin b cos b的值 cos平方a-cos平方b=A -cos｛a+b｝乘以cos｛a-b｝Bcos｛a+b｝乘以cos｛a-b｝C-sin｛a+b｝乘以sin｛a-b｝Dsin｛a+b｝乘以sin｛a-b｝要过程 证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2B=1 sin(a-b)*cos a-cos(a-b)*sin a=1/5,则cos 2b的值是 当a=3π/4时,sin(a+b)+cos(a+b)+sin(a-b)+cos(a-b) 非线性方程解析解-x0*cos(b)*cos(c)-y0*(-sin(a)*cos(b)*cos(c)-cos(a)*sin(c))-z0*(-cos(a)*cos(b)*cos(c)+sin(a)*sin(c))=0-x0*cos(b)*sin(c)-y0*(-sin(a)*cos(b)*sin(c)+cos(a)*cos(c))-z0*(-cos(a)*cos(b)*sin(c)-sin(a)*cos(c))=0 -x0*cos(b)-y0*sin(a)*co 化简COS(a+B)COS(a-B)+sin平方B