Question 114912
a diameter is twice the radius, actually two radii end-to-end


the two end points given in the queation could be end points of diameters, depending on which end another radius is added


going from O to R, adds 3 to the x value and -1 to the y; so the other end of a diameter starting at O would be (5,1)


similarly, R to O is -3 in x an 1 in y; the other end of a diameter starting at R would be (-4,4)