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

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Co₃ = Ishta-hṛti = K/12 H cos z = (H cos z)/(H cos φ) = (cos z)/(cos φ) (11)
Co₃ = Śanku-tala = s/12 H cos z = H cos z tan φ
= (H cos z H sin φ)/(H cos φ) = R cos z tan φ (12).
From the triangle PZS, we have the formula
sin δ = sin φ cos z + cos φ sin z sin a written under verse 8
∴ (sin δ)/(cos φ) = cos z tan φ + sin z sin a or in the Hindu form
(R sin δ)/(cos φ) = H cos z tan φ + (H sin z H sin a)/R . I.
We saw under verse 8 that (R sin δ)/(H cos φ) = (RH sin δ)/(H cos φ)
= Agrajyā (formula 5). Also we have from (12) above
H cos z tan φ = Śanku-tala. From fig. 40, if SM be drawn
secondary to the prime-vertical, the right-angled spherical
triangle SMZ gives
[L14