Posted by **A** on Sunday, November 13, 2011 at 12:42pm.

A light is on the ground 20m from a barn. A 2m tall llama walks from the light directly toward the side of the barn at 1m/s. How fast is the height of the llama's shadow on the barn changing when he's 14m from the barn? (draw and label a nice diagram first!)

- College Calculus -
**Steve**, Monday, November 14, 2011 at 12:28am
If x is the diatsnace from the light to the llama, and h is the height of the shadow on the wall, then using similar triangles,

h/20 = 2/x

hx = 40

At 14m from the barn, x=6 and h = 40/6 = 20/3

hx' + xh' = 0

(20/3)(1) + 6h' = 0

h' = -10/9

## Answer This Question

## Related Questions

- Geometry - A cow is tethered by a piece of rope 50 meters long to the side of a...
- Calculus - A bright light on the ground illuminates a wall 12 meters away. A man...
- Calculus - A bright light on the ground illuminates a wall 12 meters away. A man...
- calculus - A bright light on the ground illuminates a wall 12 meters away. A man...
- math - a ladder is 12 feet laid on the side of the barn. its base from the ...
- math - A cow is tethered by a piece of rope 50 meters long to the side of a ...
- Calculus - A street light is hung 18 ft. above street level. A 6-foot tall man ...
- Math: pre calculus - a barn is 150 feet long and 75 feet wide. the owner has 240...
- diffirential calculus - a woman 6ft tall walks away from a light 10ft above the ...
- calculus - A woman 5.5 ft tall walks at a rate of 6 ft/sec toward a streetlight ...

More Related Questions