Answer: 12km
Step-by-step explanation:
To find the missing side you need to use the formula a^2 + b^2 = c^2 where C is your hypotenuse.
So your formula would be 4^2 + 3^2 = c^2 ...
16 + 9 = c^2
25 = c^2 so square root both sides. Your missing side is 5km and then add all sides together to find your perimeter.
