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

176 (3) Why H cos δ is called Dyujyā in formula II is clear from fig. 20 wherein p is the celestial pole, (C) is the Fig. 20 celestial Equator and (C) is the diurnal circle of a celestial body say the ☉ ie. the Sun. Let ☉N be the perpendicular dropped from ☉ on the plane of the Equator so that ☉N = H sin ☉A = H sin δ CN = H cos δ = C☉ = radius of the diurnal circle called Dyujyā (Dyu = day) द्युवृत्तत्रिज्या = द्युज्या (Madhyamapadalōpi Samāsa) formulae IV, V and VI will be dealt with in the next chapter Triprasnādhyāya more elaborately but one has to under- stand what Charajyā is to follow the subsequent verses of this chapter so that we shall give its location and defini- tion in the light of fig. 21. Let fig. 21 represent the celestial sphere in which SEN = Horizon, Z = Zenith, N = Nadir Ez = prime vertical EQR = celestial equator.