First you draw the positions of the boats compaired to the shore ane each other to find out that the angle between the boats is 110 degrees. You can use the law of cosines. c^2 = a^2 + b^2 - 2ab Cos(C). Where c is the side you are looking for, a is the side of one boat, b is the side of the other boat, and C is the angle inbetween. You will find that you have c^2 = 2^2 + 5^2 -2(2)(5) Cos(110) That reduces to c^2 = 29 - 20 Cos(110). c^2 = 48.9804. The final answer is c = 6.9986.