The equation `(x^2)/(1-r)-(y^2)/(1+r)=1,r >1,` represents (a)an ellipse (b) a hyperbola (c)a circle (d) none of these

The equation (x^2)/(2 - r) + (y^2)/(r - 5) + 1 = 0 represent an ellipse iff

x^2/(r^2-r-6)+y^2/(r^2-6r+5)=1 will represent the ellipse if r lies in the interval

The locus of the point of intersection of the tangent at the endpoints of the focal chord of the ellipse (x^2)/(a^2)+(y^2)/(b^2)=1 ( b < a) (a) is a an circle (b) ellipse (c) hyperbola (d) pair of straight lines

A normal to the hyperbola (x^2)/4-(y^2)/1=1 has equal intercepts on the positive x- and y-axis. If this normal touches the ellipse (x^2)/(a^2)+(y^2)/(b^2)=1 , then a^2+b^2 is equal to (a)5 (b) 25 (c) 16 (d) none of these

The slopes of the common tanents of the ellipse (x^2)/4+(y^2)/1=1 and the circle x^2+y^2=3 are (a) +-1 (b) +-sqrt(2) (c) +-sqrt(3) (d) none of these

The sides A Ca n dA B of a A B C touch the conjugate hyperbola of the hyperbola (x^2)/(a^2)-(y^2)/(b^2)=1 . If the vertex A lies on the ellipse (x^2)/(a^2)+(y^2)/(b^2)=1 , then the side B C must touch (a)parabola (b) circle (c)hyperbola (d) ellipse

If x^2+y^2+z^2=r^2,t h e ntan^(-1)((x y)/(z r))+tan^(-1)((y z)/(x r))+tan^(-1)((x z)/(y r)) is equal to (a) pi (b) pi/2 (c) 0 (d) none of these

If in a triangle (1-(r_1)/(r_2))(1-(r_1)/(r_3))=2 then the triangle is right angled (b) isosceles equilateral (d) none of these

A parabola is drawn with focus at one of the foci of the ellipse (x^2)/(a^2)+(y^2)/(b^2)=1 . If the latus rectum of the ellipse and that of the parabola are same, then the eccentricity of the ellipse is (a) 1-1/(sqrt(2)) (b) 2sqrt(2)-2 (c) sqrt(2)-1 (d) none of these

The curve represented by the equation sqrt(p x)+sqrt(q y)=1 where p ,q in R ,p ,q >0, is a circle (b) a parabola an ellipse (d) a hyperbola