### Home > AC > Chapter 16 > Lesson 16.9.2.2 > Problem 9-84

9-84.

Two submarines left the Long Beach Shipyard, one at a speed of 25 knots and the other at a speed of 35 knots. Their courses diverged by 35°. After 3 hours, how far apart are they? (Note: A knot is a measure of speed defined as one nautical mile per hour. A nautical mile is 1,852 meters or 1.852 kilometers.) Homework Help ✎

Draw and label a diagram.

Use the Law of Cosines.

*c*^{2} = *a*^{2} + *b*^{2} − 2*ab*cos*C*

*c*^{2} = 105^{2} + 75^{2} − 2(105)(75)cos(35°)