Originally Posted by

**SteveC**
This is how I am solving the problem.

The pole is 12 feet tall. Call the distance from the pole to the man x, and call the distance from the man to the tip of his shadow k.

By similar triangles

12/(x + k) = h/k (h is man's height)

Cross multiply

12k =hx + hk

Differentiate

12(dk/dt) + h(dx/dt) + h(dk/dt)

After this point I am picking an arbitrary value for (dx/dt) and (dk/dt), but making sure that the value I pick for dk/dt is twice as big as dx/dt. (his shadow moves twice as fast as he does)

I get 8 ft. for the mans height after this, but I honestly think that it should be 6 feet. What kind of textbook would have an 8ft. tall man as the answer to a question. The answers are usually realistic.