sinacosb+cosasinb=1/2
sinacosb-cosasinb=1/3
所以sinacosb=5/12
cosasinb=1/12
相除
(sina/cosa)*(cosb/sinb)=5
(sina/cosa)/(sinb/cosb)=5
tana/tanb=5
sinacosb+cosasinb=1/2
sinacosb-cosasinb=1/3
所以sinacosb=5/12
cosasinb=1/12
相除
(sina/cosa)*(cosb/sinb)=5
(sina/cosa)/(sinb/cosb)=5
tana/tanb=5