Jeffrey K. answered • 09/01/20

BS in Math and Computer Science with 20+ years of tutoring experience

The first step should be to draw a diagram of the situation. You should end up with a right triangle with the lion and man at the ends of the hypotenuse, the fence as one side, and the ground between the fence and the lion as the other side. You know the angle of elevation (the angle where the lion is, which is the same as the angle of depression from the man to the lion) and the length of the opposite side (the fence). The distance from the man to the lion is the length of the hypotenuse, and the relationship between that value and the other two values you know is a simple trig function.