50 POINTS !!
PLEASE HELP !! ILL GIVE BRAINLIEST TO THE RIGHT ANSWERS.

Answer:
4.123 km
Step-by-step explanation:
a squared = c sqaured - b squared
a squared = 9 sqaured - 8 squared
a squared = 81 - 64
a squared = 17
a = root 17
a = 4.123 km