# Help with Ellipse Problem

• July 4th 2007, 09:32 AM
andy11
Help with Ellipse Problem
The Ellipse (x^2/9)+(y^2/16)=1 is _________

A) A vertical ellipse with foci at (0, +-sqroot7)
B) A horizontal ellipse with foci at (+-sqroot7, 0)
C) An ellipse with a minor axis of length 8
D) An ellipse with a major axis of length 6

thanks
• July 4th 2007, 10:05 AM
Soroban
Hello, Andy!

We can "eyeball" the equation . . .

Quote:

The ellipse . $\frac{x^2}{9}+ \frac{y^2}{16} \:=\:1$ .is:

(A) A vertical ellipse with foci at $(0,\,\pm\sqrt{7})$
(B) A horizontal ellipse with foci at $(\pm\sqrt{7},\,0)$
(C) An ellipse with a minor axis of length 8
(D) An ellipse with a major axis of length 6

We see that the major (longer) axis is in the y-direction, a "vertical" ellipse.
. . The length of the major axis is 8; the minor axis has length 6.

This eliminates answer-choices $(B),\,(C),\,(D)$

• July 4th 2007, 10:07 AM
andy11
thanks