Respuesta :

use formula: a^2 + b^2 = c^2

c is the hypotenuse, so c = 24.01
b is 20.5

plug into formula:
a^2 + (20.5)^2 = (24.1)^2

simplify and solve:
a^2 + 420.25 = 580.81
a^2 = 160.56

a = 12.671 miles