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PAGE: 108 | SET: Exercises | PROBLEM: 19 |

(a) Build a model that expresses the distance between the cars as a function of time
.
At , the cars are
miles south and
miles east of the intersection, respectively.
Draw the related diagram.
A is moving at a constant speed of miles per hour.
B is moving at a constant speed of miles per hour.
If is in hours,
is the distance travelled with the speed
mph at time
.
is the distance travelled with the speed
mph at time
.
The distance from car A to the intersection is .
The distance from car B to the intersection is .
Apply Pythagorean theorem, .
.
(b)
Graph the function .
Locate the minimum point on the graph.
is smallest when
hr.
(a) .
(b) is smallest when
hr.

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