00:03
Okay, to find the epicenter of the earthquake, we want to find the point of intersection of the three circles.
00:09
So i'm going to start by sketching the circles.
00:11
And if you have compass and graph paper, that's even better for accuracy.
00:17
So the first circle is going to have center to four and radius five.
00:22
So we can sketch that.
00:24
Plot the center and then from there, up five, right five, down five, left five.
00:30
And we get our sketch.
00:34
The second circle has center 1, negative 3, and radius 5.
00:39
So we can plot that point, 1, negative 3, and then up 5, right 5, down 5, left 5.
00:49
We have our circle.
00:52
And then the third one has center negative 3, negative 6, and radius 10.
00:57
So negative 3, negative 6.
00:59
And then we're going to go 10 and write 10.
01:06
I'm probably not gonna be able to make the whole circle, but we get something like that.
01:13
And so we're looking for where these all intersect and it's likely to be somewhere around here.
01:19
So to find that point with algebra, what we're going to do is take our three equations, change their form a little bit, and then solve the system.
01:26
So i'm going to multiply the equation out and get x squared minus 4x plus 4, plus y squared minus 8y plus 16 equals 25 and when i combine some like terms and simplify that i get x squared minus 4x plus y squared minus 8y equals 5 for the second equation multiplying it out gives us x squared minus 2x plus 1 plus y squared plus 6y plus 9 equals 25 and that simplifies to be x squared minus 2x plus y squared plus 6y equals 15.
02:10
And for the third one, multiplying it out gives us x squared plus 6x plus 9 plus y squared plus 12y plus 36 equals 100...