The length of a diagonal from one corner of the garden to the opposite corner is equal to the square root of the sum of the squares of the lengths of the sides of the garden. So, the length of the diagonal is about 20.2 meters.
Here's the solution:
Let d be the length of the diagonal.
We know that the length of the garden is 15 m and the width of the garden is 13.70 m.
We can use the Pythagorean theorem to find the length of the diagonal:
d^2 = 15^2 + 13.70^2
d = sqrt(15^2 + 13.70^2)
d = sqrt(225 + 187.69)
d = sqrt(412.69)
d = 20.2 m (rounded to the nearest tenth)