Cách 1: $\sin\alpha=\dfrac{\sqrt 3}{2}$
$↔\alpha=60^\circ$
$\cos\alpha=\cos 60^\circ=\dfrac{1}{2}$
$\tan\alpha=\tan 60^\circ=\sqrt 3$
$\cot\alpha=\cot 60^\circ=\dfrac{\sqrt 3}{3}$
Vậy $\cos\alpha=\dfrac 1 2,\,\tan\alpha=\sqrt 3,\,\cot\alpha=\dfrac{\sqrt 3}{3}$
Cách 2: $\sin\alpha=\dfrac{\sqrt 3}{2}$
$↔\sin^2\alpha=\dfrac{3}{4}$
mà $\sin^2\alpha+\cos^2\alpha=1$
$→\cos^2\alpha=\dfrac{1}{4}\\↔\cos\alpha=\dfrac{1}{2}(\text{với}\,\,\alpha\,\,\text{nhọn})\\\tan\alpha=\dfrac{\sin\alpha}{\cos\alpha}=\dfrac{\dfrac{\sqrt 3}{2}}{\dfrac{1}{2}}=\sqrt 3\\→\cot\alpha=\dfrac{1}{\tan\alpha}=\dfrac{1}{\sqrt 3}=\dfrac{\sqrt 3}{3}$
Vậy $\cos\alpha=\dfrac 1 2,\,\tan\alpha=\sqrt 3,\,\cot\alpha=\dfrac{\sqrt 3}{3}$
