Word problems with differentiation (implicit, I think)

Doing homework/studying for test tomorrow.

"A street light is at the top of an 11 foot pole. A woman 6 feet tall walks away from the pole with a speed of 8 ft/sec along a straight path. How fast is the tip of her shadow moving when she is 50 feet from the base of the pole?"

It includes a hint that says, "you should draw a picture of a right triangle with the vertical side representing the pole, and the other end of teh hypotenuse representing the tip of the woman's shadow. Where does the woman fit into this picture? Label her postion as a variable, and labelthe tip of her shadow as another variable. You might like to use similar triangles to find a relationship between these two variables."

Problem is, I have no idea HOW to state the relationship between the two triangles I am supposed to draw. Could anyone point me in the right direction? I'm fine with implicit differentiation and everything--just stuck on this one. Thanks.