**A man 6 feet tall walks at a rate of 5 feet per second toward a street light that is 16 feet tall. At what rate is the length of his shadow changing when he is 10 feet from the base of the light?**

**Answer:**

draw a line from light top to man top extentending to ground.

. a triangle is formed . let size of shadow be x and distance between man and pole be y at any time t.

u see that . x/(x+y)=6/16

or 5x=3y

differentate wrt t

5dx/dt=3dy/dt

dy/dt= 5

5dx/dt=15

dx/dt=3