[tex]\displaystyle
\lim_{n\to \infty} n \tan \dfrac{1}{n}=\\\\
\lim_{n\to \infty} \dfrac{ \tan \dfrac{1}{n}}{\dfrac{1}{n}}=\\\\
\lim_{x\to 0} \dfrac{ \tan x}{x}=\\\\
\lim_{x\to 0} \dfrac{ \dfrac{\sin x}{\cos x}}{x}=\\\\
\lim_{x\to 0} \dfrac{\sin x }{x \cos x}=\\\\
\lim_{x\to 0} \left(\dfrac{\sin x}{x}\cdot\dfrac{1}{ \cos x}\right)=\\\\
1\cdot1=\\
1[/tex]