Question

（2012•大豐市二模）數(shù)軸上點(diǎn)A、B的位置如圖所示，若點(diǎn)A關(guān)于點(diǎn)O的對(duì)稱(chēng)點(diǎn)為A₁，若點(diǎn)B關(guān)于點(diǎn)O的對(duì)稱(chēng)點(diǎn)為B₁，則線(xiàn)段A₁B₁的長(zhǎng)度為

4

Answer 1

分析：先根據(jù)點(diǎn)A、B表示的數(shù)得到線(xiàn)段AB的長(zhǎng)為4，由于點(diǎn)A關(guān)于點(diǎn)O的對(duì)稱(chēng)點(diǎn)為A₁，若點(diǎn)B關(guān)于點(diǎn)O的對(duì)稱(chēng)點(diǎn)為B₁，則A₁B₁=AB=4．

解答：解：∵點(diǎn)A、B表示的數(shù)分別為-1，3，
∴線(xiàn)段AB的長(zhǎng)=3-（-1）=4，
∵點(diǎn)A關(guān)于點(diǎn)O的對(duì)稱(chēng)點(diǎn)為A₁，若點(diǎn)B關(guān)于點(diǎn)O的對(duì)稱(chēng)點(diǎn)為B₁，
∴A₁B₁=AB=4．
故答案為4．

點(diǎn)評(píng)：本題考查了實(shí)數(shù)與數(shù)軸：數(shù)軸上的點(diǎn)與實(shí)數(shù)一一對(duì)應(yīng)．也考查了數(shù)軸上兩點(diǎn)之間的距離．