00:01
Okay, the rectangle is x, y, x, y, right? so we're trying to make the perimeter small, as small as possible.
00:11
So 2 times x plus y is the perimeter, right? and the area is x times y, which is 1000.
00:21
So this is your primary equation and this is your secondary equation, okay? so from the secondary equation, solve for x or y, it doesn't matter, because they are almost identical.
00:34
And then plug it in, into the first equation.
00:39
So perimeter is 2y times 2x which is 1000 over y.
00:49
And now take the derivative of this with respect to y, which is 2 minus 2000 over y squared.
00:58
Set it to 0...