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)

$\pm 4$

Answer 2

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