Question

The sum of the focal distances of any point on the conic $\frac{x^2}{25}+\frac{y^2}{16}=1$ is

• A. 10
• B. 9
• C. 41
• D. 18

Answer 1

Answer: (A)

10

Answer 2

We know, if $P$ is any point on the curve, then Sum of focal distances =length of major axis
i.e., $SP + S' P =2 a$
$=2(5)\left[\because a ^{2}=5^{2}\right]$
$=10$