In a previous article, we saw how the area of a circle, and the volume of a sphere are computed using Kerala School methods. We had not looked at the surface area of a sphere at that point, since we had not looked at jyā yet. Now that that is familiar to us, it is …

# Monthly Archives: July 2021

## जीवे परस्परन्यायः – The sin(A+B) rule and some trigonometric reasoning

Alongside calculus, the Kerala School also came up with some interesting results in Trigonometry, including the now commonly known method to calculate the sines (ज्या) of the sums are difference of two angles (arcs): जीवे परस्परनिजेतरमौर्विकाभ्याम् अभ्यस्य विस्तृतिदलेन विभज्यमाने ।।अन्योन्ययोगविरहानुगुणे भवेतांयद्वास्वलम्बकृतिभेदपदीकृते द्वे ।। 1) The two jyā (of the two arcs), multiplied by the kojyā …

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