Answer: sqrt(85)/2
Step-by-step explanation:
Remember that the length of the diameter is twice that of the radius.
The first step would be finding the distance between the two points using the distance formula[tex]\sqrt{(x_2 - x_1)^{2} + (y_2 - y_1)^{2}[/tex].
The distance of diameter = [tex]\sqrt{85}[/tex]
The distance of the radius would be half that, so [tex]\frac{\sqrt{85}}{2}[/tex]
