00:01
We've been given another ellipse x squared over 225 plus y squared over 144, and that is equal to 1.
00:15
And we are tasked with finding the foci for each equation.
00:20
So the foci, we're using this equation again, c squared equals a squared minus b squared.
00:26
And we are, an a squared is 225, and b squared is 144, because we're right.
00:34
We're always using the bigger number at the beginning.
00:37
So we get 81.
00:39
So that means c is plus or minus the square root of 81, and that is plus or minus 9.
00:45
And then, again, those values are going to be, in this case, x values, but they're always just whatever the bigger number was that we drew.
00:53
That's where they are.
00:54
They're always along the major axes.
00:56
So it's 9 and 0 and minus 9 and 0.
00:59
And then we're asked to graph it...