सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

431
the parallax in latitude either of the Sun or the Moon is
equal to 4/R H sin of the zenith-distance of the respective
Vitribhalagna wherever the Sun or the Moon be situated
in their orbits namely the Ecliptic or the Vimandala. Let
H sin ZV be the Dṛk-kṣepa of the Sun, V being the
Vitribhalagna pertaining to the Sun and let H sin Zv
be the Dṛk-kṣepa of the Moon where v is the Vitribha-
lagna of the Moon. (Ref. figures 98 and 99) Let K' be
the pole of the Vimandala and vv₂ the latitude of v. Since
v and V are in the proximo, the latitude of v may be
taken to be very nearly equal to the latitude of V so that
ZV ± latitude of V is very nearly equal to Zv. In fig. 98,
ZV—latitude of V is very nearly equal to Zv because both
ZV and latitude of V are of the same direction. In fig. 99
ZV+latitude of V is very namely equal to Zv because both
arc of opposite direction. Thus Zv = ZV ± latitude of V
approximately and H sin ZV and H sin Zv are the Dṛk-
kṣepas of the Sun and the Moon respectively. Having
got these Dṛk-kṣepas 4/R × Dṛk-kṣepa gives the nati in
each case ie. the parallax in latitude and the sum or
difference of these natis as mentioned in the beginning of
the commentary of this verse gives the relative parallax
of the Moon with respect to the Sun which is called the
Fig. 98 Fig. 99