The value of $k$, for which the function $f(x)= \begin{cases}\left(\frac{4}{5}\right)^{\frac{\tan 4 x}{\tan…
The value of $k$, for which the function
$f(x)= \begin{cases}\left(\frac{4}{5}\right)^{\frac{\tan 4 x}{\tan 5 x}} & , 0 \lt x \lt \frac{\pi}{2} \\ \mathrm{k}+\frac{2}{5} & , x=\frac{\pi}{2}\end{cases}$
is continuous at $x=\frac{\pi}{2}$, is