Question

If the area of the Ellipse is $\frac{x^2}{25}+\frac{y^2}{{\lambda }^2}=1$ is $20\pi$ square units, then $\lambda$ is

• A. $\pm 4$
• B. $\pm 3$
• C. $\pm 2$
• D. $\pm 1$

Answer 1

Answer: (A)

$\frac{x^2}{25}+\frac{y^2}{{\lambda }^2}=1$
$\pi ab=\pi \cdot 5\cdot |\lambda |=20\pi$
$|\lambda |=4\Rightarrow \lambda =\pm 4$