How do you write the equation of a circle if you are given only the endpoints of a radius of the circle.

If you are given only endpoints of a radius of a circle, then you need to figure out which of the given point is the center of the circle. this is probably given to you, otherwise you might have to choose one.next is to figure out the length of the radius. this is done via the distance formula.the distance between two points  and  is given by    the distance between the end points will therefore be the radius of the circle.then, use the standard equation of  a circle.for a circle centered at  with a radius of  , the equation is    where  you get from the distance formula.