Posted by Thien Nguyen on Friday, April 26, 2013 at 1:04am.
An observer is located on the ground 6 kilometers from the point where a space shuttle is launched (vertically). When the shuttle is 8 kilometers high, it is travelling at 500 kilometers per hour. Determine, for that moment, the rate at which the distance between the observer and the shuttle is changing.

math  Steve, Friday, April 26, 2013 at 10:55am
draw a diagram. The distance from the observer to the shuttle when the height is y, is
d^2 = 6^2 + y^2
2d dd/dt = 2y dy/dt
when y=8, d=10 so
20 dd/dt = 2(8)(500)
dd/dt = 400 km/hr