## Algebra and Trigonometry 10th Edition

$\frac{x^2}{81}+\frac{y^2}{9}=1$
Major axis is horizontal. $(±9,0)=(±a,0)$ $a=9$ $2b=6$ $b=3$ Standard form when major axis is horizontal: $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$ $\frac{x^2}{9^2}+\frac{y^2}{3^2}=1$ $\frac{x^2}{81}+\frac{y^2}{9}=1$