Question 138876
A car is traveling on a road that is perpendicular to a railroad track.  When the car is 30 meters from the crossing, the car's new collision detector warns the driver that there is a train 50 meteres from the car and heading toward the same crossing.  How far is the train from the crossing?
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Draw the picture.
You should have a right triangle with hypotenuse 50 meters 
and a side of 30 meters.
The other side is the distance of the train from the intersection.
Call the missing side "x".
EQUATION:
50^2 = 30^2 + x^2
x = sqrt[50^2-30^2]
x = sqrt[2500-900]
x = sqrt[1600]
x = 40 meters (the distance the train is from the crossing)
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Cheers,
Stan H.