`#0409`

Ta có `:` `sin^2\alpha+cos^2\alpha=1`

`sin^2\alpha=1-cos^2\alpha=24/25`

`sin\alpha=(2\sqrt{6})/5` hoặc `sin\alpha=-(2\sqrt{6})/5`

`@` Nếu `sin\alpha=(2\sqrt{6})/5` thì `:`

`cot\alpha=(cos\alpha)/(sin\alpha)=(1/5)/((2\sqrt{6})/5)=(\sqrt{6})/12`

`tan\alpha=1/(cot\alpha)=1/((\sqrt{6})/12)=2\sqrt{6}`

`@` Nếu `sin\alpha=-(2\sqrt{6})/5` thì `:`

`cot\alpha=(cos\alpha)/(sin\alpha)=(1/5)/(-(2\sqrt{6})/5)=(-\sqrt{6})/12`

`tan\alpha=1/(cot\alpha)=1/(-(\sqrt{6})/12)=-2\sqrt{6}`