Science:Math Exam Resources/Courses/MATH104/December 2012/Question 05 (b)/Hint 3

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Bob's distance to the lamp is y and so the speed he is walking is

.

What do we expect the sign of this number to be in the end?

Use similar triangles for the triangles mentioned in hint 1 using the picture from part (a) and relate all these hints to create a solution.