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 + (95h)^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  Two cars, car X and car Y , start moving from the same point P on a cross...
 Calculus  1)A north south highway, intersects an east west highway, at point P...
 Calculus  Two cars leave an intersection at the same time. Car X is travelling ...
 Calculus  Two cars leave an intersection at the same time. Car X is travelling ...
 Calculus  Two cars leave an intersection at the same time. Car X is travelling ...
 math  A boat is travelling south at a rate of 18 km/h. A man walks across the ...
 Trigo  Two men travelling in opposite directions at the rate 18 and 22 miles ...
 Physics  A 1500kg blue car is travelling south, and a 2000kg red sports car ...
 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