A 4-foot tall child walks away from a 12-foot street light at a rate of 2 feet per second. At what
rate is the length of her shadow increasing when she is 6 feet away from the light? Homework Help ✎
Sketch the situation. Your sketch should have similar right triangles.
If the child's distance from the light is d and their shadow length is s, then:
The equation can be rewritten as 2s = d.
Now use the information given in the problem to solve for ds/dt.