A projector, laying on the ground, illuminates the wall of a building standing 15 m away. A person 1.6 m tall walks from the projector to the wall. We would like to determine the rate at which the person's shadow decreases the moment the person is 3 m from the wall, given that, at that moment, the person is walking toward the wall at 0.9 m/s. To solve this problem, let .9: be the distance in meters between the walker and the wall, 1; the height of their shadow in meters, and t the time in seconds. (a) Sketch a diagram and use similar triangles to express 3; as a function of m . y = IEm d (b) What is the value of dz: at the moment in question? Give its value with two decimals precision, paying attention to the sign. dy "_--' Number m/s dt