History of Hindu Mathematics: A Source Book v2.c17.s19.t1.31

v2.c17.s19.t1.31

Bhâskara II³ illustrates by taking the right triangles (3, 4, 5) and (5, 12, 13) so that the resulting cyclic quadrilateral is (25, 39, 60, 52). The same example was given before by Mahâvîra¹ and Pṛthûdakasvâmî.² This cyclic quadrilateral also appears in the *Triśatikâ* of Śrîdhara³ and in the commentary of the *Āryabhaṭîya* by Bhâskara I (522). The diagonals of this quadrilateral are, states Bhâskara II, 56 (= 3.12 + 4.5) and 63 (= 4.12 + 3.5) (Fig. 7). He then observes: