An intuitive method by a 6th century mathematician
Brahmagupta in his Brāhmasphuṭasiddhānta gives an method by which we can find Rsin(θ/2) from R cos θ which can be found from R sin θ.
The verse that deals with this is:
This verse translates to:
“The square root of the fourth part of the Versed Rsine of an arc multiplied by the diameter is the Rsine of half that arc.”
This is equivalent to:
Reference : Brāhmasphuṭasiddhānta, Chapter XXI,23
