I am working radioastronomy and have a formula for sun/earth calculation.
The formula for sun begin with $20(\cos270 \cos 30 \ldots\ldots+$
Question:
The first part is $\cos270=0$ and is that correct in the formulas attached.
https://advlabwiki.johnshopkins.edu/images/Vlsr.pdf
Vr(sun) = 20.0 [cos 270° cos 30° cos α cos δ + sin 270° cos 30° sin α cos δ + sin 30° sin δ] (km/s)