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

284 PZ = colatitude ; PS = north-polar-distance or co-decli- nation. η is called the parallactic angle ; h = hour-angle of S. (90 — a) = The complement of the Hindu azimuth a being measured from the East point. cos (90 — δ) = cos (90 — φ) cos z + sin (90 — φ) sin z cos (90 — a) sin δ = sin φ + cos z + cos φ sin z sin a (1) cos z = cos (90 — φ) cos (90 — δ) + sin (90 — φ) × sin (90 — δ) cos h = sin φ sin δ + cos φ cos δ cos h (2) cos (90 — φ) cos (90 — a) = sin (90 — φ) cot z — sin (90 — a) cot h ie. sin φ sin a = cos φ cot z — cos a cot h (3) cos (90 — φ) cos h = sin (90 — φ) cot (90 — δ) — sin h × cot (90 — a) ie. sin φ cos h = cos φ tan δ — sin h tan a (4) sin z sin (90 — δ) ─────── = ───────────── ie. sin z cos a = sin h cos δ (5) sin h sin (90 — a) This means in modern terms cos z = sin φ sin δ + cos φ cos δ cos h V which we derive from the triangle PZS. Verse 58. To get H cos z from h the hour-angle or nata Kāla. The H. vers (Nata) is called Sara (CQ of fig. 52) (29) Antyā — Śara = Iṣṭāntyā ie. FQ — CQ = FC = AN (fig. 51) H cos δ Śara × Kujyā Śara × ───────── = ───────────── = phala (CQ) (fig. 53) R Charajyā (30)