Answer:
A-0.5777miles
B-0.7223miles
Step-by-step explanation:
Let A be truck with 58°, B be truck with 52° elevation and C be the position of the fire. We know that the AB is 1.3 miles apart.
-Using sine rule, we find the length of AB and BC as:

#Bisect angle C, and use sine rule again to find the lengths of bisected AB:

Truck B's position is calculated as 1.3mi-0.5777miles=0.7223miles
Hence, truck one is 0.5777miles and truck two is 0.7223 miles from the fire.