The equation of the ellipse having a vertex at $(6,1)$, a focus at $(4,1)$ and the eccentricity…

The equation of the ellipse having a vertex at $(6,1)$, a focus at $(4,1)$ and the eccentricity $\frac{3}{5}$ is
  1. $\frac{(x-1)^2}{16}+\frac{(y-1)^2}{25}=1$
  2. $\frac{(x-1)^2}{25}+\frac{(y-1)^2}{16}=1$
  3. $\frac{(x+1)^2}{25}+\frac{(y+1)^2}{16}=1$
  4. $\frac{(x+1)^2}{16}+\frac{(y+1)^2}{25}=1$

Solution

Let the equation of ellipse is, $ \frac{(x-h)^2}{a^2}+\frac{(y-k)^2}{b^2}=1 $ Now, $ \begin{array}{rlrl} a-a e & =2 \\ \Rightarrow & a\left(1-\frac{3}{5}\right) & =2 \Rightarrow a=5 \\ & \text { So, } & b & =4 \end{array} $ So, Now, vertex comparing the vertex, we are getting $ \text { and } \quad \begin{aligned} & 6-h=5 \Rightarrow h=1 \\ & 1-k=0 \Rightarrow k=1 \end{aligned} $ So, equation of required ellipse is $ \frac{(x-1)^2}{25}+\frac{(y-1)^2}{16}=1 . $

Asked in: AP EAMCET 2018 (23 Apr Shift 2)

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