Answer
$\frac{x^2}{36}+\frac{y^2}{9}=1$
Work Step by Step
Step 1. Based on the given conditions, we have $a=\frac{12}{2}=6, b=\frac{6}{2}=3$.
The ellipse is centered at $(0,0)$ with a horizontal major axis.
Step 2. We can write the equation as $\frac{x^2}{36}+\frac{y^2}{9}=1$
