DPP-2 CONIC SECTIONS
1. The equation \(a x^2+2 h x y+b y^2+2 g x+2 f y+c=0\) represents a rectangular hyperbola if
a) \(\Delta \neq 0, h^2>a b, a+b=0\)
b) \(\Delta \neq 0, h^2<a b, a+b=0\)
c) \(\Delta \neq 0, h^2=a b, a+b=0\)
d) None of these
2. The line passing through the extremity \(A\) of the major axis and extremity \(B\) of the minor axis of the ellipse \(x^2+9 y^2=9\) meets its auxiliary circle at the point \(M\). Then, the area of the triangle with vertices at \(A, M\) and the origin \(O\) is
a) \(\frac{31}{10}\)
b) \(\frac{29}{10}\)
c) \(\frac{21}{10}\)
d) \(\frac{27}{10}\)
3. From the point \((-1,-6)\) two tangents are drawn to the parabola \(y^2=4 x\). Then, the angle between the two tangents is
a) \(30^{\circ}\)
b) \(45^{\circ}\)
c) \(60^{\circ}\)
d) \(90^{\circ}\)
4. The centre of the ellipse \(4 x^2+9 y^2+16 x-18 y-11=0\) is
a) \((-2,-1)\)
b) \((-2,1)\)
c) \((2,-1)\)
d) None of these
5. The circle whose equation are \(x^2+y^2+c^2=2 a x\) and \(x^2+y^2+c^2-2 b y=0\) will touch one another externally if
a) \(\frac{1}{b^2}+\frac{1}{c^2}=\frac{1}{a^2}\)
b) \(\frac{1}{c^2}+\frac{1}{a^2}=\frac{1}{b^2}\)
c) \(\frac{1}{a^2}+\frac{1}{b^2}=\frac{1}{c^2}\)
d) None of these
6. In an ellipse the distance between the foci is 8 and the distance between the directrices is 25 . The length of major axis is
a) \(10 \sqrt{2}\)
b) \(20 \sqrt{2}\)
c) \(30 \sqrt{2}\)
d) None of these
7. If \(l x+m y+n=0\) represents a chord of the ellipse \(b^2 x^2+a^2 y^2=a^2 b^2\) whose eccentric angles differ by \(90^{\circ}\), then
a) \(a^2 l^2+b^2 m^2=n^2\)
b) \(\frac{a^2}{l^2}+\frac{b^2}{m^2}=\frac{\left(a^2-b^2\right)^2}{n^2}\)
c) \(a^2 l^2+b^2 m^2=2 n^2\)
d) None of these
8. If the latusrectum of a hyperbola forms an equilateral triangle with the vertex at the centre of the hyperbola, then the eccentricity of the hyperbola is
a) \(\frac{\sqrt{5}+1}{2}\)
b) \(\frac{\sqrt{11}+1}{2}\)
c) \(\frac{\sqrt{13}+1}{2 \sqrt{3}}\)
d) \(\frac{\sqrt{13}-1}{2 \sqrt{3}}\)
9. The eccentricity of the conic \(4 x^2+16 y^2-24 x-32 y=1\) is
a) \(\frac{1}{2}\)
b) \(\sqrt{3}\)
c) \(\frac{\sqrt{3}}{2}\)
d) \(\frac{\sqrt{3}}{4}\)
10. If the chords of contact of tangents from two points \(\left(x_1, y_1\right)\) and \(\left(x_2, y_2\right)\) to the hyperbola \(4 x^2\) \(-9 y^2-36=0\) are at right angles, then \(\frac{x_1 x_2}{y_1 y_2}\) is equal to
a) \(\frac{9}{4}\)
b) \(-\frac{9}{4}\)
c) \(\frac{81}{16}\)
d) \(-\frac{81}{16}\)
11. The equation of a circle which cuts the three circles
\[
\begin{aligned}
& x^2+y^2-2 x-6 y+14=0 \\
& x^2+y^2-x-4 y+8=0 \\
& x^2+y^2+2 x-6 y+9=0
\end{aligned}
\]
orthogonally, is
a) \(x^2+y^2-2 x-4 y+1=0\)
b) \(x^2+y^2+2 x+4 y+1=0\)
c) \(x^2+y^2-2 x+4 y+1=0\)
d) \(x^2+y^2-2 x-4 y-1=0\)
12. The length of the common chord of the ellipse \(\frac{(x-1)^2}{9}+\frac{(y-2)^2}{4}=1\) and the circle \((x-1)^2+\) \((y-2)^2=1\) is
a) 2
b) \(\sqrt{3}\)
c) 4
d) None of these
13. The mirror image of the directrix of the parabola \(y^2=4(x+1)\) in the line mirror \(x+2 y=3\), is
a) \(x=-2\)
b) \(4 y-3 x=16\)
c) \(x-3 y=0\)
d) \(x+y=0\)
14. The line \(x=a t^2\) meets the ellipse \(\frac{x^2}{a^2}+\frac{y^2}{b^2}=1\) in the real points, if
a) \(|t|<2\)
b) \(|t| \leq 1\)
c) \(|t|>1\)
d) None of these
15. The length of the latusrectum of the hyperbola \(\frac{x^2}{a^2}-\frac{y^2}{b^2}=-1\), is
a) \(\frac{2 a^2}{b}\)
b) \(\frac{2 b^2}{a}\)
c) \(\frac{b^2}{a}\)
d) \(\frac{a^2}{b}\)
16. The condition that the chord \(x \cos \alpha=0+y \sin \alpha-p=0\) of \(x^2+y^2-a^2=0\) may subtend a right angle at the centre of the circle is
a) \(a^2=2 p^2\)
b) \(p^2=2 a^2\)
c) \(a=2 p\)
d) \(p=2 a\)
17. Given that circle \(x^2+y^2-2 x+6 y+6=0\) and \(x^2+y^2-5 x+6 y+15=0\) touch, the equation to their common tangent is
a) \(x=3\)
b) \(y=6\)
c) \(7 x-12 y-21=0\)
d) \(7 x+12 y+21=0\)
18. The number of common tangents of the circles \(x^2+y^2-2 x-1=0\) and \(x^2+y^2-2 y-7=0\) is
a) 1
b) 2
c) 3
d) 4
19. A ray of light incident at the point \((-2,-1)\) gets reflected from the tangent at \((0,-1)\) to the circle \(x^2+y^2=1\). The reflected ray touches the circle. The equation of the line along which the incident ray moved is
a) \(4 x-3 y+11=0\)
b) \(4 x+3 y+11=0\)
c) \(3 x+4 y+11=0\)
d) None of these
20. If the points \(A(2,5)\) and \(B\) are symmetrical about the tangent to the circle \(x^2+y^2-4 x+4 y=0\) at the origin, then the coordinates of \(B\) are
a) \((5,-2)\)
b) \((1,5)\)
c) \((5,2)\)
d) None of these