Tangents are drawn from any point on the circle x2+y2=41 to the ellipse x225+y216=1 then the angle between the two tangents is
x2+y2=41=25+16
∴x2+y2=a2+b2 is the director circle of
x2a2+y2b2=1
Since director circle is the locus of intersection of perpendicular tangents.
∴ angle between the tangents is π2