Quadrilateral ABCD has an inscribed circle which touches sides AB,BC,CD and DA at W,X,Y and Z respectively. If AB=14cm, BC=11cm and CD=6cm,
(i) Prove that AW=AZ, BW=BX, CX=CY and DY=DZ.
(ii) Using these relations, find the length of side DA.
(iii) Determine the perimeter of quadrilateral ABCD.