SOLUTION: The points (-3,-1) and (9,4) are the endpoints of the diameter of a circle. Find the length of the radiu of the circle. I have used the midpoint equation to get (3,3/2) as the

Algebra ->  Circles -> SOLUTION: The points (-3,-1) and (9,4) are the endpoints of the diameter of a circle. Find the length of the radiu of the circle. I have used the midpoint equation to get (3,3/2) as the       Log On


   

Question 483783: The points (-3,-1) and (9,4) are the endpoints of the diameter of a circle. Find the length of the radiu of the circle.
I have used the midpoint equation to get (3,3/2) as the mid point. So now I was using the standard equation of a circle to try an get the radius but I seem to be doing something wrong. The answer in my book says it is 6.5 but I keep getting 6.25 or 6.2. I would Rely like to see all the steps taken to get the answer. Can u help me?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Distance between ywo points (x1,y1) & (x2,y2)
is given by the formula
d=+sqrt%28%28x1-x2%29%5E2%2B%28y1-y2%29%5E2%29
plug the values
d=+sqrt%28%28-3-9%29%5E2%2B%28-1-4%29%5E2%29
d=sqrt%28%28-12%29%5E2%2B%28-5%29%5E2%29
d=+sqrt%28%28144%2B25%29%29
d=sqrt%28169%29
d=13
so you know the radius now.
m.ananth@hotmail.ca