Co-ordinate of mid-point of A(a, b), B(a’, b’) are
\((\frac{a+a'}{2},\frac{b+b'}{2})\), and co-ordinate of mid-point of
C(– a, b), D(a’, – b’) are \((\frac{-a+a'}{2},\frac{b-b'}{2})\). Now, the equation of the line passing through (x1, y1) and (x2, y2) is
y − y1 = \(\frac{y_2-y_1}{x_2-x_1}\) (x− x1)
Here,
⇒ 2b’ x – 2ay + (ab – a’ b’ + ab’) = 0, is the required equation of the line.