of polar coordinates (r, ). The reverse process, however, is not so sim. basis es (,y) on the ple. The radius can be computed by the following formula: If the coordinates lie in the first or fourth quadrant (that is, ifx > 0), then the following simple formula can be used to compute e: 8tan1 0, The fol- The difficulty arises with the other two quadrants and when x lowing table summarizes the possibilities: tang) tan-2 + 2 'Write a well-structured Sub procedure to compute (r, 0), given (x,y). Express the final results for in degrees. The following is the start of the problem: Sub Polar Dim x a Double, y As Double, r as Double, th As Double End Sub