3. A person standing 3 feet away from the base of a lamp post casts a shadow 4 feet long. If the person is 6 feet tall and walks away from the lamp post at a speed of 400 feet per minute, at what rate will his shadow lengthen

533.33 ft/min

Step-by-step explanation:

We are given that

x=3 feet

y=4 feet

Height of person,h=6 feet

Triangle ABC and A'B'C are similar because all right triangles are similar

By using similarity property

Differentiate w.r.t t

Hence, If the person is 6 feet tall and walks away from the lamp post at a speed of 400 feet per minute then his shadow moving at the rate 533.33 ft/min