



 
Hi Chelsey, I would always draw a diagram. S is a ship, L is the top of the lighthouse and B is its base. The angle of depression, that is the angle between the line of sight and horizontal is 5^{o}. Since the surface of the water is parallel to the line labeled horizontal the measure of the angle LSB is 5^{o} also. Thus you have a right triangle LSB, you know the measure of the angle LSB, the length of the side opposite angle LSB (60 m) and you want to know the length of the side SB which is adjacent to the angle LSB. The trig function that relates the angle, the opposite side and the adjacent side is the tangent. Thus it's the tangent function you want for this problem. I hope this helps,  


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