Respuesta :

If we determine the distance from one point to  the second point, we get the length of the diameter. This is calculated through the equation,

  D= sqrt ((x2 – x1)^2 + (y2 – y1)^2)

Substituting the known values,

  D = sqrt ((-1 – 3)^2 + (1 – 3)^2)

  D = 4.47

The length of the radius is half that of the diameter. Hence, the radius is,

    R = 4.47 /2 = 2.236

Answer: r = 2.24