- Home
- Standard 11
- Mathematics
10-2. Parabola, Ellipse, Hyperbola
medium
If the co-ordinates of two points $A$ and $B$ are $(\sqrt{7}, 0)$ and $(-\sqrt{7}, 0)$ respectively and $P$ is any point on the conic, $9 x^{2}+16 y^{2}=144,$ then $PA + PB$ is equal to
A
$8$
B
$6$
C
$16$
D
$9$
(JEE MAIN-2020)
Solution
$\frac{x^{2}}{16}+\frac{y^{2}}{9}=1$
$a =4 ; b =3 ; e =\sqrt{\frac{16-9}{16}}=\frac{\sqrt{7}}{4}$
A and $B$ are foci
$\Rightarrow PA + PB =2 a =2 \times 4=8$
Standard 11
Mathematics