Clarification

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Clarification

by vladmire » Sun Dec 07, 2008 12:47 pm
In the xy-plane, each point on circle K has nonnegative coordinates and the center of K is the point (4,7). What is the maximum possible area of K?
4pi
9pi
16pi
28pi
49pi

The way I went about solving this was to draw a xy-grid so the circle was in quadrant I. Because all of the points on the circle are positive. Then the radius is 4, because the center of circle is 4 away from the x axis. Area of a circle is a=pir^2 so 4^2=16 or 16pi cannot be any larger right cause the points must all be positive.
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by kris610 » Sun Dec 07, 2008 2:16 pm
I'll go with 16pi. Draw perpendiculars from the center to the x and y axes--then take whichever is less.