Posted by **Teri** on Friday, June 8, 2012 at 2:19pm.

a man 6ft tall walks at the rate of 5ft/sec toward a streetlight that is 16ft above the ground. At what rate is the length of his shadow changing when he is 10ft from the base of the light?

- Math -
**Steve**, Friday, June 8, 2012 at 3:17pm
If the shadow is length y when the man is x feet from the pole, then using similar triangles,

y/6 = (x+y)/16

y = 3x/5

dy/dt = 3/5 dx/dt = 3/5 (-5) = -3

so, the shadow is shrinking at 3 ft/sec regardless of the distance from the pole.

## Answer this Question

## Related Questions

Calculus- rates - A man 6ft. tall walks at the rate of 5 ft/sec toward a ...

calculus - A woman 5.5 ft tall walks at a rate of 6 ft/sec toward a streetlight ...

Calculus - A man is 6ft tall and is walking at night straight toward a lighted ...

math - A man 6 feet tall walks at a rate of 5 feet/sec toward a street lamp that...

Calculus - (It's a related rate question) A man 6ft tall walks away from a lamp ...

diffirential calculus - a woman 6ft tall walks away from a light 10ft above the ...

Calculus-rates - 1.) A man 6 ft tall walks at a rate of 5 ft per sec. from a ...

Calculus - Shadow Length A man 6 feet tall walks at a rate of 3 ft per second ...

Calculus - A woman 5 ft tall walks at the rate of 5.5 ft/sec away from a ...

calculus - My problem is that a stft above the sidewalk. a man 6ft tall walks ...