Question

A hiker is lost in the woods. A search team has created a coordinate grid to represent the woods. Each unit on the grid is one square mile. The hiker was last seen at (4, -9) and could have walked 10 miles in any direction since then. Which equation represents the area the hiker could be in?

A) (x - 4)2 + (y + 9)2 = 102
B) (x + 4)2 + (y - 9)2 = 102
C) (x + 4)2 + (y + 9)2 = 1002
D) (x - 4)2 + (y - 9)2 = 1002

Answer 1

The circle of radius r centered at (h, k) has equation
.. (x -h)^2 +(y -k)^2 = r^2

Selection A is appropriate.

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It would be helpful if you would use appropriate math symbols. 102 is very different from 10^2. (Copying and pasting does not work--editing is needed.)