Question

Cho 0\(^0\) < α < 90\(^0\) , cos α =\(\frac{3}{5}\) .Tính cos α, tan α, cot α

Answer 1

Lời giải:

Ta có:

$\sin ^2a=1-\cos ^2a=1-(\frac{3}{5})^2=\frac{16}{25}$

$0< a< 90$ nên $\sin a>0$. Do đó $\sin a=\frac{4}{5}$

$\tan a=\frac{\sin a}{\cos a}=\frac{4}{5}: \frac{3}{5}=\frac{4}{3}$

$\cot a=\frac{1}{\tan a}=\frac{3}{4}$