IIT JEE , AIEEE Forum - Mathematics , Analytical Geometry - conics-8

Sivvar

The set of positive values of 'm' fr which a line with slope 'm' is a common tangent to ellipse x^2/b^2 + y^2/c^2 =1 n the parabola y^2=4ax is:

(a) (3,5)

(b) (2,3)

(c) (1,3)

(d) (0,1)

???

skmonga.hbk

let y=mx+a is a tangent 2 ellipse x^2/b^2+y^2/c^2=1 then a^2=b^2m^2+c^2

if y=mx+a is also tangent 2 y^2=4ax then a^2=a^2/m^2 equating values of a^2 we get values of m