若cos(a+b)=-1,tan a=2,求cot b的值

若cos(a+b)=-1,tan a=2,求cot b的值
若cos(a+b)=-1,tan a=2,求cot b的值

若cos(a+b)=-1,tan a=2,求cot b的值
cos(a+b)=-1,tan a=2,求cot b的值
cos(a+b)=-1
a+b=180度+k*360度,k为整数
cosb=-cosa
sinb=sina
cot b=cosb/sinb=-cosa/sina=-1/tana=-1/2

cos(a+b)=-1,
sin(a+b)=0
tan(a+b)=0
tan(a+b)
=(tana+tanb)/(1-tanatanb)=0
tana+tanb=0
2+tanb=0
tanb=-2
cotb=-1/2