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two cars begin a trip from the same point
if car A travel north at the rate of 30 and car B travel west at the rate 40
how fast rate distance between them changing 2 hrs later
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From your post, I see that you are not able to write the dimension of speed correctly.
It tells me, how far your knowledge goes on the subject ( ! ).
THEREFORE, I changed it myself from min/h to miles/h.
One leg of the right angled triangle is 30*t miles long (where "t" denotes the time).
Other leg is 40*t miles.
The hypotenuse is = = 50*t.
The hypotenuse is the distance between the cars, and it is proportional to the time.
So, the rate of changing the distance is 50 miles per hour, and it does not depend on time.
It is constant and is equal to 50 miles per hour always, until the cars move according to the given rule
(and until we can consider the spherical Earth surface as flat). ANSWER
Solved, explained, answered and completed.
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By the way, the question formulation in your post is not a proper English,
so it is difficult to understand what you really ask about.
Therefore, I will not even try to interpret your question (because it is impossible).
I only will give my answer in two different forms, that express the same thought:
(1) the distance between the cars is changing at the constant rate of 50 mph,
which does not depend on time.
(2) the rate of changing the distance between the cars is 50 miles per hour and does not change in time.