Two submarines, one cruising at 25 knots and the other at 20 knots, left a naval base at the same moment. three hours later, they were 100 nautical miles apart. what was the measure of the angle between their courses?

Step-by-step explanation:

Speed of submarine 1 = 25 knots = 28.77 mph

Speed of submarine 2 = 20 knots = 23 mph

Time taken = 3 hours

Distance traveled by submarine 1 = 28.77 x 3 = 86.31 miles

Distance traveled by submarine 2 = 23 x 3 = 69 miles

Distance between them is 100 nautical miles = 115.08 miles

Refer the figure

        By cosine formula we have

                               a = 86.31 miles

                               b = 115.08 miles  

                               c = 69 miles  

Substituting

Measure of the angle between their courses  is 95°