Question

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的對稱點(diǎn)為A₁，若點(diǎn)B關(guān)于點(diǎn)O的對稱點(diǎn)為B₁，則線段A₁B₁的長度為   

Answer 1

【答案】分析：先根據(jù)點(diǎn)A、B表示的數(shù)得到線段AB的長為4，由于點(diǎn)A關(guān)于點(diǎn)O的對稱點(diǎn)為A₁，若點(diǎn)B關(guān)于點(diǎn)O的對稱點(diǎn)為B₁，則A₁B₁=AB=4．
解答：解：∵點(diǎn)A、B表示的數(shù)分別為-1，3，
∴線段AB的長=3-（-1）=4，
∵點(diǎn)A關(guān)于點(diǎn)O的對稱點(diǎn)為A₁，若點(diǎn)B關(guān)于點(diǎn)O的對稱點(diǎn)為B₁，
∴A₁B₁=AB=4．
故答案為4．
點(diǎn)評：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)一一對應(yīng)．也考查了數(shù)軸上兩點(diǎn)之間的距離．