3.14x(4x4-2x2)x25x7.8=3.14x12x25x7.8=9.42x100x7.8=942x7.8=7351.6公斤
4/2的平方*π =6.282/2的平方*π=3.146.28-3.14=3.143.14*7.8=24.492
78kg