2015 TWO(d)

ExcellenceComprehensive
Question
A street light is 5 m above the ground, which is flat.

A boy, who is 1.5 m tall, is walking away from the point directly below the streetlight at
2 metres per second.

At what rate is the length of his shadow changing when the boy is 8 m away from the point
directly under the light?

*You must use calculus and show any derivatives that you need to find when solving this
problem.*
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