Solution:
We have re-drawn the given diagram, as we can see the given rectangle is actually divided into two parts.
one is Large square and the other one is a smaller rectangle.
Now we will apply the Pythagoras theorem in the larger triangle which is inside the square.
So we can write
Now we will apply the Pythagoras theorem in the smaller triangle which is inside the smaller rectangle.
So we can write
The approximate sum of the lengths of the two sidewalks, shown as dotted lines m
Hence the correct option is D
