
Graphs of Circles in Center Radius Form Math Help Game Tips:  The circle represented by x^{2}+y^{2}=r^{2} has the center point P(0,0) and has the radius r units.  The circle represented by (xh)^{2}+(yk)^{2}=r^{2} has the center point P(h,k) and has the radius r units.  When comparing the circles x^{2}+y^{2}=3^{2} and (x4)^{2}+(y1)^{2}=3^{2}, the two circles have the same size radius=3 and (x4)^{2}+(y1)^{2}=3^{2} is shifted four units East and one unit North compared to x^{2}+y^{2}=3^{2}. The circle (x4)^{2}+(y1)^{2}=3^{2} has the center (4,1).  When comparing the circles x^{2}+y^{2}=9 and (x+5)^{2}+(y1)^{2}=9, the two circles have the same size radius=3 and (x+5)^{2}+(y1)^{2}=9 is translated five units in the negative x direction and translated one unit in the positive y direction compared to x^{2}+y^{2}=9. The circle (x+5)^{2}+(y1)^{2}=9 has the center (5,1) and the radius r=3.  The game can be played using the mouse by itself or using the keyboard by itself.  If the game doesn't respond to keyboard input, click inside the game area to reset the game's focus.  Adjust the game's speed by pressing the + or  key repeatedly. 
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