00:01
Two cars start moving from the same point.
00:04
One travels south at 60 miles per hour and the other travels west at 25 miles per hour.
00:09
At what rate is the distance between the cars increasing two hours later? let's solve our problem by drawing a diagram.
00:18
Let's say both of our cars start at the origin.
00:28
The first car travels south at a speed of 60 miles per hour.
00:44
The second car travels west at a speed of 25 miles per hour.
00:54
We can see in this configuration that the distance between two cars corresponding to the octagonal distance here, this distance, will increase in time.
01:05
The goal is to find an expression for this distance that depends on time and to differentiate it to find its rate of change two hours later.
01:15
To do so, we need to characterize these two adjacent lengths.
01:22
Let's say that this distance is equal to x of t and the other distance south is y of t.
01:33
Let's put the positive x -axis right and the positive y -axis down...