Length of the straight line x − 3y = 1 intercepted by the hyperbola x2 − 4y2 = 1 is
Intercept is the distance between
the points of intersection between the line and the hyperbola.
(3y + 1)2 − 4y2 = 1
9y2 + 1 + 6y − 4y2 − 1 = 0
5y2 + 6y = 0
y(5y + 6) = 0
y = 0 or −65
x=1 or −185 + 1
points of intersection are
(1,0) and (−135,−65)
Intercept=√(1+135)2 + (65)2
=√18225 + 3625
=6√105
Hence option (d)