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

484 cos z = sin ϕ sin δ + cos ϕ cos δ cos h Put z = 90 + θ, h = 90 + H, δ = δ in the positions A, B and z = 90−θ, h=90−H. δ=−δ in the positions A', B' We have then − sin θ = sin ϕ sin δ − cos ϕ cos δ sin H and sin θ = − sin ϕ sin δ + cos ϕ cos δ sin H which are identical. This means that the altitude θ below the horizon with +δ in the positions A, B is computable with −δ in the positions A', B'. This accounts for the statement made ‘गोलविपर्ययेण’. The second statement of the latter half of verse (2) says Śankutala = Śanku × ˢ/₁₂ which we have proved in Tripraśnādhyāya. Verse (3) and first half of (4). To obtain the Bhuja of the Sun. The Śankutala of the inverse altitude or the altitude below the horizon, is north (in contradistinction to what it is above the horizon). The sum or difference of the Agrā and Śankutala according as they are of the same direction or of opposite directions, is the Bhuja. The sum or difference of the Bhujas of the Sun and Moon, according as they are of opposite or the same directions is what is called the Spaṣṭa Bhuja whose direction is to be construed as that of the Moon. If the Bhuja of the Moon falls short of that of the Sun, then the direction of the Spaṣṭa Bhuja is that opposite to that of the Moon. Comm. In fig. 113, we have shown five different positions of the Sun S₁ to S₅ the feet of the Śankus being B₁ to B. From these feet of the Śankus draw perpendiculars on the Udayāstasutras as well as on the East-west line their points of intersection being respectively A₁ to A₅ and C₁ to C₅. The perpendiculars from the feet of the Śankus on the East-west line go by the name Bhujas, the perpendi-