Question

PSP’ is a focal chord of the ellipse $16x^2+25y^2=400.$ If SP = 8 then SP’ =

• A. $1$
• B. $2$
• C. $3$
• D. $4$

Answer 1

The correct option is B $2$

$\frac{1}{SP}+\frac{1}{S{P}^{\prime }}=\frac{2}{l}\Rightarrow \frac{1}{8}+\frac{1}{S{P}^{\prime }}=\frac{10}{16}\Rightarrow S{P}^{\prime }=2$