Question 612594
The center is the mid point 
 If the coordinates of A and B are ( x1, y1) and ( x2, y2) respectively, then the midpoint, M, of AB is given by the following formula																						
(-2,1)(8,5)   													
M(x,y) ={{{(x1+x2)/2}}}	{{{(y1+y2)/2}}}															
x=	(-2+8)/	2y=(1+	5	)/	2									
x=	3		,y=	3																		
(	3	,	3	)  	

Radius is the distance from center to one of the endponts of the diameter .
Distance between two points													
x1	y1	x2	y2										
													
(3	3)	(8	5)										
d=	{{{sqrt((y2-y1)^2+(x2-x1)^2)}}}												
d=	{{{sqrt((5-3)^2	+(8-3)^2)}}}
d=	{{{sqrt((2)^2+(5)^2)}}}				
d=	{{{sqrt((29))}}}								
d=	5.39												
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