初三数学,几何证明题,高手赐教!答:⑴⑵是⑶的特款。直接证明⑶。如图取坐标系,使D(0,0),C(2,0)B(2,2),A(0,2).设F(2a,2b),则M(a,b)[DF中点],N(-b,a)[正方形]E(a-b,a+b).G(a+1,b+1).CG斜率=(b+1)/(a-1)。 EG斜率=(1-a)/(1+b),∵[(b+1)/(a-1)]×[(1-...
3M胶带原装真品去哪找?答:3M9139HT, 3M9802-100, 3M9802-85, 3M9172MP, 3M9185MP, 3M920XL, 3M921XL, 3M9313B黑/白, 3M9313BT, 3M936BK黑/白, 3M936BLUE黑/,3M9372DK, 3M9502HL, 3M9505HL, 3M9598BF, 3M9599, 15919819625 张先生 3M9667MP, 3M9668MP, 3M9676MP, 3M969, 3M9832HL, 3M9925XL, 3M9926XL...