Question

 點(diǎn)A(1,2,-3)關(guān)于x軸的對(duì)稱點(diǎn)B的坐標(biāo)為         , 點(diǎn)A關(guān)于坐標(biāo)平面xOy的對(duì)稱點(diǎn)C的坐標(biāo)為         , B,C兩點(diǎn)間的距離為           ．

 

Answer 1

【答案】

 (1,-2,3 )   (1,2,3)    4　　解析：過(guò)A作AM⊥xOy交平面于M，并延長(zhǎng)到C,使CM=AM，則A與C'關(guān)于坐標(biāo)平面xOy對(duì)稱且C(1,2,3)．

過(guò)A作AN⊥x軸于N，并延長(zhǎng)到點(diǎn)B，使NB=AN，則A與B關(guān)于x軸對(duì)稱且B(1,-2,3)．

∴A(1,2,-3)關(guān)于x軸對(duì)稱的點(diǎn)B(1,-2,3 )．

又A(1,2,-3)關(guān)于坐標(biāo)平面xOy對(duì)稱的點(diǎn)C(1,2,3);

∴|BC|==4．