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

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V are congruent because AZ = A'Z and ZV is common
∴ AV = VA'. But AV + VA' = 180° because the Ecliptic
and the horizon being two great circles, they bisect each
other. Hence AV = 90°. Then a celestial body situated at
V will be depressed along ZV the vertical, say, to a point B.
Let ☉ be any arbitrary position of the Sun; then ☉ will
be depressed along the vertical Z☉, say, to a point C.
Draw CD perpendicular on the Ecliptic. Then ☉D is the
component of the parallax ☉C along the Ecliptic where
as DC is its component perpendicular to the Ecliptic.
Thus ☉D is the parallax in longitude and DC is the
parallax in latitude. The word ‘Lambana’ means
etymologically लम्बते अनेनेति लम्बनम् ie. that amount by
which the celestial body is depressed (along the Ecliptic).
In Hindu Astronomy the word Lambana is applied to
parallax in longitude alone whereas the word Nati is
applied to parallax in latitude. Hence to translate
Lambana as parallax alone is not correct. The word
Drik-lambana is applied to mean parallax along the
vertical, and the word Sphutalambana is occasionally used
to connote parallax in longitude.
As Bhāskara rapidly comments on the verses in this
Gaṇitādhyāya, he having dealt with the subject of parallax
elaborately under the caption, Grahaṇa Vāsanā, in the
Golādhyāya, to catch up his thought, we have to treat the
subject first from the modern view point and then elucidate
what he has said in the Golādhyāya, much matter of which
is reiterated by him under the commentary here in the
Gaṇitādhyāya.
(Ref. Fig. 91) From the △EAM,
(sin EMA) / a = (sin EÂM) / d = (sin ZÂM) / d where a is the radius of
the Earth and d the distance of the celestial body (here the
Moon)