Something

 public void mGetInput(double dTSide1, double dTSide2, double dTSide3)
   {

     System.out.print ("Please enter length of side 1 (left side): ");
     dTSide1 = scan.nextDouble();

     System.out.print ("Please enter length of side 2 (right side): ");
     dTSide2 = scan.nextDouble();

     System.out.print ("Please enter length of side 3 (bottom): ");
     dTSide3 = scan.nextDouble();

   }