Can you show us how you got that line?
I'm getting (taking r as a constant):
find the dimensions of the rectangle of largest area that can be inscribed in a circle of radius r
area of the rectangle = 2x2y
y = root(r^2-x^2)
x=r or x=-r/2
plugging x back into area formula
area = 4(-r/2)[root(r^2-r^2/4)]
area = -r(root3r^2)
the answer is that the sides are [root(2)]r, and that it is actually a square.
Not sure what I'm doing wrong..
also, what happened to the Latex tutorial...?