解：
S 下=（2.4m+3.4m）×2×0.25m=2.90m
2
S 上=[0.5×0.7-0.4×0.6]+(0.5+2.4) ×（1.35
2
+0.2
2
）
1/2
×2/2+(0.7+3.4) ×(0.95
2
+0.2
2
)
1/2
×2/2=0.11+3.96+3.98=8.05m
2
3
/
29
解：
S 下=（2.4m+3.4m）×2×0.25m=2.90m
2
S 上=[0.5×0.7-0.4×0.6]+(0.5+2.4) ×（1.35
2
+0.2
2
）
1/2
×2/2+(0.7+3.4) ×(0.95
2
+0.2
2
)
1/2
×2/2=0.11+3.96+3.98=8.05m
2
3
/
29