/1 - cos(4*x)\ lim |------------| x->oo\2*x*tan(2*x)/
Limit((1 - cos(4*x))/(((2*x)*tan(2*x))), x, oo, dir='-')
/1 - cos(4*x)\ lim |------------| x->0+\2*x*tan(2*x)/
2
= 2.0
/1 - cos(4*x)\ lim |------------| x->0-\2*x*tan(2*x)/
2.0