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