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

422 In fig. 92, H sin Z☉ is in the form of a Karṇa; H sin ZV is in the form of the corresponding Bhuja. This triangle formed by these two as sides may be taken to be similar to the triangle ☉DC, both being called parallax Δs. This plane triangle ☉DC is like the plane triangle which has for its sides H sin λ, H sin δ, where λ and δ are the longitude and declination of a point of the Ecliptic. In the Triprasnādhikara, we had occasion to deal with this triangle and there we had R √(H sin² λ - H sin² δ) --------------------- H sin α where α is the right ascen- H cos δ √(H sin² Z☉ - H sin² ZV) sion of the point. Similarly R ------------------------ H cos ZV = H sin V☉. In other words Dṛk-nati is H sin V☉ projected into a circle of radius H cos ZV from a circle of radius R. We have the proportion ∴ C☉ CD D☉ -------- = ------------- = ------------------------- H sin Z☉ ☉ sin ZV √(H sin² Z☉ - H sin² ZV) D☉ = Sphutalambana = ------------------------- √(H sin² Z☉ - H sin² ZV) The quantity under the radical in the denominator is called Dṛk-nati for the following reasons. When V coincides with Z, V ☉ is the Dṛk-mandala- nata, so that when V is deflected also, we continue to view the Dṛk-nati placed along V☉. Since Madhyama- lambana ☉C is in the form of a Karṇa in the Δ ☉DC, we perceive it to be in the form of a Karṇa even when V coincides with Z. This Madhyamalambana being equal to Sphutalambana when V coincides with Z, Sphuta- lambana is also in the form of a Karṇa then. Now in the position ☉DC, Sphutalambana has assumed the position of a Kōti ie. the Sphutalambana which, in the form of a Karṇa, being placed along Dṛk-mandala natāmsa, is now