Cho biết tanα=12\tan\alpha = \dfrac{1}{2}tanα=21. Tính cotα\cot\alphacotα.
cotα=2\cot\alpha = \sqrt{2}cotα=2.
cotα=2\cot\alpha = 2cotα=2.
cotα=14\cot\alpha = \dfrac{1}{4}cotα=41.
cotα=12\cot\alpha = \dfrac{1}{2}cotα=21.
cotα=1tanα=112=2\cot \alpha = \frac{1}{{\tan \alpha }} = \frac{1}{{\frac{1}{2}}} = 2cotα=tanα1=211=2.
