Posted by **angel** on Thursday, April 5, 2012 at 7:49am.

A____________B 9 miles is between A and B?

at 3pm Andy began travelling South at a rate of 4mi/hr from point A

at the same time Bill began travelling West at a rate of 5mi/hr from point B to A

both stop wlking when Bill reaches point A

What time will the distance between Bill and Andy be minimized?

- calc -
**Steve**, Thursday, April 5, 2012 at 12:03pm
Let A be (0,0) and B = (9,0)

The distance d between Bill and Andy after h hours can be found using

d^2 = (4h)^2 + (9-5h)^2

= 16h^2 + 81 - 90h + 25h^2

= 41h^2 - 90h + 81

d = √(41h^2 - 90h + 81)

dd/dh = (82h - 90)/√(41h^2 - 90h + 81)

dd/dh = 0 when h = 90/82 = 1.1 hr = 1:06

3:00 + 1:06 = 4:06

## Answer this Question

## Related Questions

- math - A boat is travelling south at a rate of 18 km/h. A man walks across the ...
- Physics - A 1500-kg blue car is travelling south, and a 2000-kg red sports car ...
- Trigo - Two men travelling in opposite directions at the rate 18 and 22 miles ...
- Calculus - 1)A north south highway, intersects an east west highway, at point P...
- Math - Tiffany can run 12 miles in the same time it takes her to bicycle 72 ...
- physics - Two cars leave the same point at the same time, each travelling at the...
- physics - Two cars leave the same point at the same time, each travelling at the...
- algebra - During rush hour, Bill can drive 60 miles using the side roads in the ...
- physics - Two cars leave the same point at the same time, each travelling at the...
- physics - Two cars leave the same point at the same time, each travelling at the...

More Related Questions