ABS value in plane-line equation?

Hi,

Math question here about finding theta between a line and a plane. I've gotten by the dot cross result for the top of the equation and am working the "magnitude" of each in the bottom part. Question: should I take the ABS of the two sqrt functions below? The tutorial showed the denominator initially having the abs symbol || but disappeared from the work up. Perhaps its assumed.

cos theta =

n dot a

------------------

sqrt(values...) sqrt(values)

Should the sqrt be | sqrt(values...)| |sqrt(values...)|