Let DX=x and the side length of a square be a, then ax = (a 2+x 2) (1/2) (that is, the square of a plus the sum of the squares of x and then open the root sign), and ay = (a 4/(x 2)+a 2) (65438+).
The following contents are used in high school knowledge: A2+B2 > = 2ab (ab > 0)
ax=(a^2+x^2)^( 1/2)>; (2ax) (1/2) (here, because A is not equal to X, it is greater than the symbol)
ay=(a^4/(x^2)+a^2)^( 1/2)>; (2a^3/x)^( 1/2)
AX+AY & gt; = 2 (AX * AY) (1/2) (that is, 2 times the root number AX times AY)
= 2 * (2a 2) (1/2) = 2 times the root number 2 * a.
And AC = (a 2+a 2) (1/2) = root number 2 * a.
So AX+AY & gt;; 2AC .
I'm really sorry, because this place is not easy to represent mathematical symbols, so it may seem a bit troublesome! -High school math teacher.