Respuesta :

Since arcsin(2/5)=x,  sin x=2/5

Here we go[tex]=sinx/(sqrt(1-sin^2x)) =(2/5)/(sqrt(1-4/5))[/tex]
[tex]tan x = sinx/cosx[/tex]
More than one way possible : 
[tex]tan(arcsin(2/5)) =(2/5)/ (sqrt(21)/5)=2/sqrt(21)[/tex]