Indian standard circle

Indian standard circle is a name given to the standard circle first used in Surya Siddhanta and later used by several ancient Indian mathematicians and astronomers to improve the Indian sine tables and for various other calculations. Surya Siddhanta provides methods for calculating the Jyā (R.sine) values. The circle uses a radius of 3,438 minutes. Surya Siddhanta calculates the first Jyā (R.sine) as 1/8th of the number of minutes(kalās) in a Rashi (zodiac sign). It says a Rashi (zodiac sign) has 1800 minutes (kalās) and thus calculates the first Jyā to a value of 225 minutes (kalās).
The Indian standard circles holds significance as it is based on number of minutes in circle thus leads to 360 degrees in a circle which is the basis of modern trigonometry. Although the Indian sine tables are not based on the degrees but rather on the R.sine (Jyā) values. The Surya Siddhanta data reflect highly sophisticated outcomes of the R.sine values. Burgess notes that it is remarkable to see that the 2nd order differences increase as the sines and each, in fact, is about 1/225th part of the corresponding sine.