Q74 / 150 · MHT CET 2010 · Mathematics

The sum of focal radii of the curve $90 x^{2}+25 y^{2}=225$ is

  • A
    5
  • Correct answer
    B
    10
  • C
    6
  • D
    3

Solution

Given curve is $9 x^{2}+25 y^{2}=225$ $\Rightarrow$ $$ \frac{x^{2}}{25}+\frac{y^{2}}{9}=1 $$ Here, $a=5, b=3$ $\therefore \quad$ Sum of focal radii $=2 a=10$

Hence, the correct answer is option: 'B'.

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