00:01
All right, on this problem, you're told that you have a gate.
00:03
The diagonal of it is 13.
00:05
And so with pythagorean theorem here, that tells us x squared plus y squared is equal to 13 squared.
00:11
13 squared is 169.
00:15
And then you're also told that around the gate, you're going around the gate here, takes 34 feet of lumber.
00:22
And so that means that would be 2x plus 2y would be 34, because you've got two sides of those x's, two sides of those ys.
00:32
Now if you divide it, this all by 2 here, that would tell us x plus y is equal to 17.
00:39
And if you take the x over, that tells us y is 17 minus x.
00:45
And the whole reason i do that is so that i can plug this thing in up there for y.
00:52
And so it tells us we have x squared plus 17 minus x squared equals 16.
01:02
For 17 minus x squared, you've got to take 17 minus x, multiply it by itself.
01:07
Okay, foil it out.
01:11
When you do that, that's going to give you 289 minus 34x plus x squared is equal 169.
01:20
I'll let you verify that, all right, but you multiply it by itself and then foil it out.
01:24
And so now we have this quadratic equation to solve here.
01:30
Now to solve this quadratic, let's combine our like terms.
01:32
So x squared plus x squared is 2x squared.
01:37
Minus 34x.
01:42
And then i need to get it equal to zero.
01:43
So let's subtract 169 over...