More similar triangles.
I will post a diagram here in a little bit.
dx/dt=-1.9 and x=4:
A spotlight on the ground shines on a wall 12 m away. If a man 2 m tall walks from the spotlight toward the building at a speed of 1.9 m/s, how fast is the length of his shadow on the building decreasing when he is 4 m from the building?
As always, thanks in advance, you guys are awesome!