A=[W+2(L+W)·VH(20H)+H(200-H)106 A=[LW+2(L+W)+H2]106 兀H(200-H/4 L/H(200-1 L6 [ 2( ) (200 ) (200 )] 10 A LW L W H H H H e  − = + +  − + −  L H(200-H) L W W H(200-H) H(200-H)/4 2 6 [ 2( ) ] 10 A LW L W H e  − = + + + 