Answer: 15 km
Step-by-step explanation:
Pythagorean triples is used for this:
Pythagorean triples= 3-4-5 (not subtraction)
Find hypotenuse (long side): Since 12 down, 9 left
a2+b2=c2
Formula: (9x9)+(12x12)=[tex]\sqrt{cxc}[/tex]
(c*c)= 81+144=225 (square root)
= 15km
