Expression 5: "T" left parenthesis, "y" , "x" , right parenthesis equals signum left parenthesis, "x" , right parenthesis squared arc tangent left parenthesis, StartFraction, "y" Over "x" , EndFraction , right parenthesis plus StartFraction, 1 minus sign left parenthesis, "x" , right parenthesis Over 2 , EndFraction left parenthesis, 1 plus sign left parenthesis, "y" , right parenthesis minus sign left parenthesis, "y" , right parenthesis squared , right parenthesis piTy,x=signx2arctanyx+1−signx21+signy−signy2π