V正=aaa h=s长/a/b S正=6aa S长=2(ab+ah+bh)
=20*20*20 =8000/25/16 =6*20*20 =2*(25*16+25*20+16*20)
=8000 =20 =2400 =2*(400+500+320)
=2*1220
=2440
2440-2400=40(要加上上单位)
V正=aaa h=s长/a/b S正=6aa S长=2(ab+ah+bh)
=20*20*20 =8000/25/16 =6*20*20 =2*(25*16+25*20+16*20)
=8000 =20 =2400 =2*(400+500+320)
=2*1220
=2440
2440-2400=40(要加上上单位)