A 1.8 m tall student is trying to escape from the minimum security prison in Tono.
She runs in a straight line towards the prison wall at a speed of 4.0 m/s. The guards
shine a spotlight on the prisoner as she begins to run. The spotlight is located on
the ground 30 m from the wall. At which rate is the prisoner's shadow on the wall
decreasing when she is 20 m from the wall?
All basic differentiation rules.
The Attempt at a Solution
This is my problem, I know how to do derivatives fine, I can't set up the equation based on the information given, I was wondering if anyone could give me clues on how to set it up?