Respuesta :

13.9 mi. is the answer to ur question
Funds
Use cosine rule:

Missing side ^2 = 15^2 + 18^2 - 2 x 15 x 18 x cos 80

Missing side ^2 = 225 + 324 - 540 x cos 80

Missing side ^2 = 549 + 59.6

Missing side = root 608.6

Missing side = 24.67

This question is wrong???