Answer:
20 m
Explanation:
First find the side length
A = s^2 for a square garden
200 = s^2
Take the square root of each side
sqrt(200) = sqrt(s^2)
sqrt(2) sqrt(100) = s
10 sqrt(2) = s
Now we can use the Pythagorean theorem to find the diagonal
a^2 + b^2 = c^2 where a and b are the side lengths a c is the hypotenuse
s^2 + s^2 = c^2
200 + 200 =c^2
400 = c^2
Take the square root of each side
sqrt(400) = sqrt(c^2)
20 = c