SOLUTION: Write an equation for a circle if the endpoints of a diameter are at (-2,-1) and (8,9)?

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Question 709993: Write an equation for a circle if the endpoints of a diameter are at (-2,-1) and (8,9)?
Answer by lwsshak3(11628)   (Show Source): You can put this solution on YOUR website!
Write an equation for a circle if the endpoints of a diameter are at (-2,-1) and (8,9)
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center of circle=midpoint of diameter endpoints.
midpoint: [(x1+x2)/2),(y1+y2)/2]
=[(-2+8)/2, (-1+9)/2]
=(3,4)
Equation of circle: (x-h)^2+(y-k)^2=r^2, (h,k)=(x,y) coordinates of center, r=radius
Find radius using one of the points on the circle (-2,-1)
(-2-3)^2+(-1-4)^2=r^2
25+25=r^2
r^2=50
equation of circle: (x-3)^2+(y-4)^2=50

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