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

421 Bhāskara's proof proceeds in two stages from first principles. In the first place when V coincides with z, Lambana is seen to be equal to 4 nādis on the horizon and zero at Z ie. it is zero when H sin Z☉ = 0 and 4 nādis, a maximum when H sin Z☉ = R. So, it is meet that Lambana should be taken to be proportional to H sin Z☉ ie. proportional to natajyā. In this context the lambana termed as Madhyamalambana is entirely along the ecliptic. It is taken to be in the form of Karṇa, because in the position of ☉C also it is in the form of a Karṇa. Then let the Ecliptic be deflected from the zenith (deflected = क्षिप्त). Vitribhalagna then being deflected from the position of Z, occupies the position of V (fig. 92). So ZV is called Dṛk-kshepa since the Ecliptic which was in the form of a Dṛk-mandala is deflected from that posi- tion. Also the circle ZV is called Dṛk-kshepa-mandala because V is deflected along that circle. Now consider the △ whose sides are H sin ZV, H cos ZV and R. H cos ZV equal to R and as such in the form of a Karṇa corresponds to the Madhyamalambana which is also in the form of a Karṇa ; when this Vitribha-Sanku assumed the form H cos ZV, ie. rendered a Kōti from its form of a Karṇa, R, the Sphutalambana is also rendered a Kōti in the form of ☉ D so that Madhyamalambana / R = Sphutalambana / H cos ZV ∴ Sphutalambana = (H cos ZV / R) Madhyamalambana = (H cos ZV / R) × (4 H sin Z☉ / R) . Then Bhāskara says that we could look at this, from another angle in the words “यदेव स्फुटलम्बनस्य कोटिरूपत्व- मुपपन्नम् etc. ”.