SOLUTION: Calculus Question-Related Rates: A North-South highway A and an East-West highway B intersect at a point C. At 11:00 AM an automobile crosses C traveling north at a speed of 70 mi

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Question 537350: Calculus Question-Related Rates:
A North-South highway A and an East-West highway B intersect at a point C. At 11:00 AM an automobile crosses C traveling north at a speed of 70 mi/hr. At that same instant, an airplane flying east at a speed of 280 mi/hr and an altitude of 7 miles is directly above the point on highway B that is 130 miles west of C. If the airplane and the automobile maintain the same speed and direction, at what rate is the distance between them changing at 11:15 AM?
-I have tried drawing pictures and tried to use similar triangles, but it seems like I am getting no where!
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
reminder: this is algebra.com...not calculus.net

the distance between the two is the diagonal of a box whose dimensions are
___ length ___ 130 + 280t
___ width ___ 70t
___ height ___ 7

t is the time after 11:00 , don't mix hrs and mins

the diagonal of a box (rectangular prism) ___ D^2 = L^2 + W^2 + H^2

find D as a function of t and differentiate