Answer:
12
Step-by-step explanation:
(r + 8)² = r² + 16²
r² + 16r + 64 = r² + 256
16r = 192
r = 12
12km
(r + 8)^2= r^2+ 16^2
r^2+ 16r + 64 = r^2+ 256
r=192/16
