History of Hindu Mathematics: A Source Book v2.c17.s19.t1.47

v2.c17.s19.t1.47

In fact, according to the sequence in which the quantities (A) are taken, there will be two varieties of Brahmagupta quadrilaterals having them as their sides : (1) one in which the two diagonals intersect at right angles and (2) the other in which the diagonals intersect obliquely. The arrangement (A) gives a quadrilateral of the first variety. For the oblique variety, the sides are in the following order : $.(p² - q²)(m² + n²), & (m² - n²)(p² + q²), / 2mn(p² + q²), & 2pq(m² + n²) ; (B)$ $or .(p² - q²)(m² + n²), & 2mn(p² + q²), / (m² - n²)(p² + q²), & 2pq(m² + n²). (C)$