Write an equation for a circle with a diameter that has end points at (-4,-1) and (-8,-9) round to the nearest tenth if necessary

 1) distance formula; d = √(x2-x1)² +(y2-y1)² . d= √(-4-8)² +(-3-7)² = > d= 2√61 

diameter = 2*radius => 2√61 =2r => r =√61 => r² =61 

midpoint of the diameter is: 

Xm= -4-8 /2 -6 => -6
Ym = -1-9 /2 -5 => -5  center of the cirlce is at (-6,-5)

general equation of a circle: (x-x1)² +(y-y1)² =r² with (x1,y1) being the center of the circle.

equation:     (x+6)+(y+5)=61