Surya Siddhanta
अभीष्टच्छाययाभ्यस्ता त्रिज्या तत्कर्णभाजिता । दृग्ज्या तद्वर्गसम्शुद्धात् त्रिज्यावर्गाच् च यत् पदम् ॥
The quotient is the drịg-jyá; the square-root of the square of the radius diminished by that of the drịg-jyá (just found), is the śanku; multiply it by the radius and divide the product by the cosine of latitude (of the place).
english translation
abhISTacchAyayAbhyastA trijyA tatkarNabhAjitA । dRgjyA tadvargasamzuddhAt trijyAvargAc ca yat padam ॥
hk transliteration by Sanscript