the picture in the attached figure 
Applying the Pythagorean Theorem 
Find the lengths of the two sidewalks 
Step 1 
square section 
D=√{15²+15²} 
D=√450 m 
D=21.21 m 
Step 2 
rectangular section 
D=√{15²+8²} 
D=√289 m 
D=17 m 
Step 3 
the sum of the lengths of the diagonals of the two sections is 
17m + 21.21 m = 38.21 m 
the answer is 
38.2 m