由重心坐标的公式：
i i
C
a x
X
G
?
=
∑
261 2.48499.2,0.3, 1.2
b b B
G kN X m Y m
=???=== ()3
0.250.47 2.224 6.39
c
a m
=+??=
6.3926166.14
c
G kN
=?=
110.25 2.228 1.810.22 2.22826.39
c C f X ???+????= 10.70.7 2.92 1.44 1.703
c C f X ++==?= 210.25 2.228 2.260.22 2.22826.39
C C f Y ???+????= 2 2.15 2.15 1.93 2.08 2.213
C C f Y ++==?= ()30.230.45 2.224 6.04
D a m =+??= 6.0426157.04D G kN =?=
20.23 2.228 1.810.50.23 2.2286.04
D f X ???+????= 10.230.230.450.3 1.743
D D f X ++==?= 20.23 2.2280.1150.50.23 2.2286.04
D f Y ???+????= 20.230.230.450.30.183D D f Y ++==?= 499.20.3166.14 1.7157.04 1.710.85499.2166.14157.04i i
a x X a
??+?+?===++∑ 499.2 1.2166.14 2.21157.040.18 1.21499.2166.14157.04i i a y
Y a ??+?+?===++∑ 则整个图形的重心在（0.85、1.3）处