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rate of change word problem?

An airplane is climbing at a 15 degree angle to the horizontal. How fast is it gaining altitude if its speed is 400 miles per hour?

So I know what the picture is supposed to look like:

http://pic90.picturetrail.com/VOL2363/11813548/209...

And I'm thinking that equation I'm supposed to use is

tan(15°) = Y/X

And I know how to take the derivative of that equation.

But the only other information I have is dX/dt = 400 mph

So how am I supposed to solve this without knowing any side lengths?

2 Answers

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  • norman
    Lv 7
    1 decade ago
    Favorite Answer

    No derivatives, a = 400 tan15

    that is the change in altitude in mph

  • 1 decade ago

    You don't need derivatives if you just use a right triangle

    a

    b . . . . . . . . . . c

    The plane is traveling from c to a on a vector of length 400

    the angle of c is 15 deg

    you are looking for the length of the vector from b to a

    Sine (c) = Opp/Hyp

    0.2588 = (ab)/400

    (ab) = 400*.2588 = 103.5

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