Question 268067
Two cars leave an intersection. One car travels east; the other north. when the car traveling east had gone 15 miles, the distance between the cars was 5 miles more than the distance traveled by the car heading north. How far had the northbound car traveled? 
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The distance between the cars is the hypotenuse of the right triangle formed by the 2 distances from the intersection.
E = 15 (eastbound car)
d^2 = E^2 + N^2
d = N + 5
(N+5)^2 = 15^2 + N^2
N^2 + 10N + 25 = 225 + N^2
10N = 200
N = 20 miles