I'm to find the acrlength parameter for s = s(t) for the path

x= e^at cos bti+ e^at sin btj+ e^atk

I do know the formula for the arclength parameter, but I'm not quite sure how the unit vectors would fit in. The formula for arclength is

s(t) = (integral from a to t)||x'(b)||db

Do I just pretend they're not there and proceed normally? Thanks!