Passage: One of Parameshvara's more significant contributions was his mean value type formula for the inverse interpolation of the sine.He was the first mathematician to give the radius of circle with an inscribed  quadrilateral. The expression is sometimes attributed to Lhuilier (1782), 350 years later. With the sides of the cyclic quadrilateral being a, b, c, and d, the radius R of the circumscribed circle is:

Question: who discovered the radius?
Lhuilier