Thursday

August 21, 2014

August 21, 2014

Posted by **Mishaka** on Thursday, January 5, 2012 at 6:00pm.

- Calculus ~ Related Rates -
**Reiny**, Thursday, January 5, 2012 at 6:52pmFrom what you said, I will assume you defined variables as such....

x is the distance between the man and the streetligh

y is the length of his shadow.

then dx/dt = -2 , find dy/dt

by similar triangles:

2/y = 5/(x+y)

5y = 2x + 2y

3y = 2x

3dy/dt = 2dxdt

dy/dt = 2(-2)/3 = -4/3

so his shadow is decreasing at a rate of 4/3 m/s

(notice , since I said "decreasing", I do not use the negative sign, since the word decreasing implies it)

**Related Questions**

calculus : related rates - a balloon rises at a rate of 3 meters per second from...

4 CALCULUS study problem - 1. How fast does the radius of a spherical soap ...

AP CALCULUS!!! HELPP - related rates: the base of a pyramid-shaped tank is a ...

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

AP CALCULUS!! HELPPP URGENT - related rates: the base of a pyramid-shaped tank ...

Math - a man 6ft tall walks at the rate of 5ft/sec toward a streetlight that is ...

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

calculus - A recatangle has constant area of 200 square meters and its lenght L ...

math - A balloon rises at a rate of 3 meters per second from a point on the ...

related rates calculus problem - A balloon is being filled with air at a rate of...