Find the radius of a circle with an area of 615.75 square kilometers

Formula for circle area = πR 2

                                       = 3.142 x R x R

               615.75             = 3.142 x R x R

             R x R                = 615.75/3.142

          Rsquared            = 195.973901973

          R                         = √195.973901973

                                      = 13.9990678966

        D                           = 2 x R

      D                             = 2 x 14 (13.999 rounded off)

                                    = 28cm

answerca air mass;