The V in the
formula is TAS. RhoVsq is IAS
1/2rho(IASsq) isn't anything
1/2rho(TASsq) aka 1/2rhoVsq is the dynamic pressure, pdyn
pstat plus pdyn is total
head aka ptot
Bernoulli says pstat plus pdyn
is a constant
Therefore the constant is total head aka ptot