=1 On differentiating both sides w.r.t. x, we get
2x
a
+
2y
b
⋅
dy
dx
=0
dy
dx
=
−bx
ay
. . . (i) Also,
x2
c
+
y2
d
=1 On differentiating both sides w.r.t. x, we get
2x
c
+
2y
d
⋅
dy
dx
=0
dy
dx
=
−dx
cy
∵ Both the curves intersect each other at 90∘. ∴ Tangents at point of intersection must be perpendicular to each other. ∴ Product of slope of tangents =−1
−bx
ay
×
−dx
cy
=−1 [from Eqs. (i) and (ii)] ⇒bdx2=−acy2 ... (iii) Also, on subtracting the equation of given curves, we get (
