Answer: 24 feet
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Explanation:
It might help to draw out a diagram. Refer to the image below. Point A is the cell tower location. Point B is where the person is located. This is a birds eye view. Point B is on the smaller circle of radius 23 ft. The cellphone, which has unknown location, is somewhere on the larger circle of radius 47 ft.
The best case scenario is that the phone is on ray AB, which would make the phone to be 47-23 = 24 ft away from the person. This is the closest the phone could be.
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Extra info:
On the flip side, the worst case scenario is that the phone is on the diametrically opposite side. This would mean the distance from the phone to the person is 47+23 = 70 ft. So the range of possible distances d is [tex]24 \le d \le 70[/tex]
