Question 54342
THIS PROBLEM IS A RIGHT TRIANGLE WITH 2 SIDES = TO 20 FEET AND THE HYPOTENUSE THE DISTANCE BETWEEN THE OPPOSITE CORNERS. THUS THE FORMULA A^2+B^2=C^2 THUS 

20^2+20^2=C^2 OR 400+400=C^2 OR  800=C^2 OR C=28.28 FEET FOR THE DIAGONAL OF THE 20 FOOT SQUARE RING.

c^2 is the same as c*c or (c squared). 800 IS THE SAME AS 28.28*28.28 or 28.28 is the square root of 800 or 800=28.28*28.28 (or 28.28^2 or 28.28 squared=800)

another example: x^2=25 or x^2=x*x & 25=5*5 thus the sqare root of x^2=x & the square root of 25=5 then x=5.